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1756 guides · updated weekly

Understand the idea, not just the headline.

In-depth guides that work through one subject at a time what it means, how it works, and what the evidence says. Every claim sourced, every guide dated.

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  • 1756

    GUIDES PUBLISHED

  • 6

    SECTIONS

  • Weekly

    REVISION CYCLE

Understanding Decision Overload and Its EffectsFEATURED

Problems & Pain Points · 21 min read

Understanding Decision Overload and Its Effects

A 2011 study of 1,112 Israeli parole rulings found favorable decisions ran about 65 percent at the start of a session and fell to nearly zero by the end, resetting after a food break, though later critiques argue case ordering partly explains it. Baumeister's work describes the same depletion: as capacity drains, the brain defaults to the easiest option or postpones. Hundreds of micro-decisions crush the few that matter.
POPULAR TOPICS Work & ProfessionalCase Studies & ExamplesDecision MakingData & ResearchProblems & Pain PointsMental ModelsLearning & Knowledge
Attention Economics ExplainedEDITOR'S PICK · Creator Economy & MediaAttention Economics ExplainedInformation became abundant while attention stayed fixed at 24 hours a day, so platforms compete for a scarce resource using infinite scroll, autoplay, variable rewards and personalization. The page traces the business model, the creator incentives it creates, and its effects on news and public discourse. Gloria Mark's research found average screen focus fell from 2.5 minutes in 2004 to roughly 47 seconds, with about 23 minutes to fully resume an interrupted task.22 min read · 34 SOURCES

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// HOW TO READ A GUIDE

Same shape every time, so you can jump straight to what you need.

Every guide is built in the same five sections. You don’t have to read top to bottom enter wherever your question is.

  • New to the ideaStart at section 1 and read through. About fifteen minutes.
  • Heard of itSkip to section 3, the evidence, and see whether it holds up.
  • About to use itGo to sections 4 and 5: where it breaks, then the checklist.
  • Checking a claimEvery study is named inline and listed in full at the end.
Read our editorial standards →

WORKED EXAMPLE · CONCEPTS

The Map Is Not the Territory

  • 01

    What it means

    Korzybski’s formulation, and the common misreading that treats it as “all models are useless.”

  • 02

    How it works

    Three ways a representation drops information: by scale, by purpose, and by whose questions it was built to answer.

  • 03

    What the evidence says

    Box on useful wrong models; Borges’s impossible one-to-one map; case studies where forgetting the gap caused real harm.

  • 04

    Where it fails

    When the map is good enough and why “the map isn’t the territory” can become an excuse to ignore data.

  • 05

    How to apply it

    A short checklist: what did this model leave out, and does the omission matter for the decision in front of you?

Read the full guide · 16 min →
Parkinson's Law: Work Expands to Fill the Time AvailableConcepts

Principles & Laws · 14 min read

Parkinson's Law: Work Expands to Fill the Time Available

C. Northcote Parkinson published the line as Civil Service satire in The Economist in November 1955, backed by arithmetic: between 1914 and 1928 Royal Navy capital ships fell by roughly two thirds while Admiralty officials rose by nearly 80 percent. His mechanism was that officials multiply subordinates and then make work for each other. The article is candid that controlled experiments isolating the law are scarce, the support being convergent.
The Welfare State: Its Origins and Impact TodayExplainers

How It Works · 16 min read

The Welfare State: Its Origins and Impact Today

Bismarck introduced compulsory health insurance in 1883, accident insurance in 1884, and old-age pensions in 1889, the world's first national social insurance system. He despised socialism and was candid about why: whoever has a pension for his old age, he told the Reichstag, is far more contented and far easier to handle. The welfare state began as a weapon against labor, not a concession to it, and that paradox never fully dissolved.
Understanding Habit Stacking for Lasting RoutinesIdeas

Habit Formation · 18 min read

Understanding Habit Stacking for Lasting Routines

How to attach a new behavior to one that already runs automatically. The formula is after I do X, I will do Y, which replaces a general intention with a specific trigger. Lally's team at UCL followed 96 volunteers and found a 66-day average to reach automaticity, with a range of 18 to 254 days. The widely repeated 21-day claim traces to Maxwell Maltz's 1960 book on patients adjusting to facial surgery and has no experimental support.
AI for Knowledge Work: Practical Workflows, Prompts, and LimitsTechnology

AI & Machine Learning · 8 min read

AI for Knowledge Work: Practical Workflows, Prompts, and Limits

Large language models generate plausible continuations rather than retrieve verified facts, which explains both their strengths and their failures. They are reliable at transforming text you provide, drafting, explaining and brainstorming, and unreliable at citations, statistics, dates and quotes, which arrive fabricated with full confidence. So supply the source material, ask for the passage behind each claim, and verify anything consequential.
Productivity Evidence Map: What the Research Actually SupportsWork & Skills

Productivity & Time Management · 19 min read

Productivity Evidence Map: What the Research Actually Supports

Task-switching cost and the benefit of short breaks are two of the better-supported findings in productivity research, yet each was disclosed by only 3 of 7 usable top search results, 42.9 percent, less often than the Pomodoro 25/5 ratio at 7 of 10, 70 percent, a claim with no controlled evidence for that specific number. This map rates each popular claim Robust, Supported, or Weak, cites the study behind it, and lists every page checked in the August 2026 measurement.
Async Communication Strategies for Distributed TeamsCulture

Work & Professional · 16 min read

Async Communication Strategies for Distributed Teams

What async-first actually requires beyond replacing meetings with chat. GitLab operates with roughly 2000 team members in more than 65 countries and no central office, publishing its handbook openly so the practices can be examined. The principles are a single source of truth, default to public, and written communication over verbal. The article is direct that documentation cost is the real tradeoff.

// WHY WE BUILT THIS

The internet got very good at answering questions badly.

So we wrote the guide we wished had come up first and kept going.

The When Notes Fly editorial team

It started as a private set of notes. We kept looking things up a mental model, a piece of history, how some system actually worked and finding the same thing: a thousand pages that ranked, and almost none that explained. The good sources were buried in papers and books; the top results were rewrites of rewrites.

So we began writing the guide we wished had come up first. One subject at a time, with the definition up front, the mechanism spelled out, the evidence named, and an honest section on where the idea stops working. When the notes started to be useful to other people, we made them public.

The library is independent. No sponsor picks the topics, and nothing is written to chase a keyword. Guides get revised when the evidence changes and the revision is dated, so you can see it.

// HOW A GUIDE EARNS ITS PLACE

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