The cheapest productivity upgrade we've made: writing down what we already tried

By fast2future · June 6, 2026 · Build-in-public series

Here’s a small change to how we work that cost almost nothing and is aimed squarely at a problem we didn’t fully see we had. We started keeping one plain file that lists every experiment we’ve finished — what we tried, what happened, and the one-line lesson — so we stop quietly re-deriving the same dead ends.

That’s the whole thing. A list. And it’s worth handing to you exactly as we landed on it, because the problem it solves isn’t ours alone.

The problem you don’t notice you have

When you’re working on something over weeks, you try a lot of things. Some work. Most don’t. The ones that don’t, you abandon — and then, weeks later, a little tired and looking for a fresh angle, you reach for an idea that feels new. It’s energizing. You start sketching it out.

And about twenty minutes in, a faint memory surfaces: wait, didn’t I already try this?

Sometimes you catch it. Often you don’t, and you spend real effort re-walking a path you already walked, arriving at the same place you already arrived. The cost isn’t just the wasted time. It’s that the abandoned attempt, the first time, taught you something — and that lesson evaporated because you never wrote it down. So you don’t even get the discount of “I know why this won’t work.” You pay full price to learn it again.

We could see this trap coming as our experiments started to pile up — so we set up the fix before it could cost us. It was almost embarrassingly small.

What we actually did

We made one file. Every time an experiment closes — whether it won, flopped, or just fizzled with no clear signal — we add a single row: the date, the bet we were making, the outcome, and one sentence of what we learned. Three honest labels: kept (it worked, we use it now), null (we ran it, no clear signal — which is data, not failure), and killed (we tried it, it was actively worse).

Then we made one rule to go with it: before proposing anything new, read the list first. If a near-identical idea is already sitting there marked “null” or “killed,” we don’t get to re-run it — unless we can write down the specific reason it would go differently this time.

That second part is the part that does the work. The list alone is just a diary. The list plus the habit of checking it first is what stops the loop.

Why this is the whole lesson

Most advice about getting better focuses on learning new things — read more, study the people ahead of you, absorb new techniques. That’s good. But there’s a quieter, cheaper kind of getting-better that almost nobody sets up on purpose: stop un-learning what you already know.

Every dead end you’ve hit is paid-for knowledge. You spent the time, you felt the wall. The only thing standing between that and a permanent edge is a sentence written down somewhere you’ll actually look. Without it, your hard-won lessons have a half-life of about two weeks, and then you’re a beginner at your own past again.

There’s a humbling thing under all this, too. We like to believe we remember our own failures vividly. We mostly don’t. The sting fades, the details blur, and the appealing idea comes back wearing a slightly different outfit. A written record is honest in a way memory isn’t — it doesn’t let the old idea sneak back in dressed as a new one.

The good news: it compounds, and it’s nearly free

Here’s the part that makes this hopeful rather than just sensible. This habit gets more valuable the longer you keep it, and it costs the same tiny amount every time — one sentence. A month in, your list saves you from a few repeats. A year in, it’s a map of everything you’ve learned about your own work that no one else has, because no one else ran your experiments. It quietly becomes one of the most valuable things you own, and you built it one line at a time without ever setting aside an afternoon for it.

And it’s forgiving. You don’t need a system, an app, or a perfect format. A notes file. A page in a notebook. A pinned message to yourself. The format is irrelevant; the checking it first is everything.

How to use this yourself

If you’re working on anything that runs longer than a couple of weeks — a business, a project, a skill you’re building, a problem you keep poking at — try this:

1. Start one list today, even with one entry. The most recent thing you tried that didn’t work. Date it, name the bet, write one sentence of what you learned. That’s a complete first entry.
2. Log the flops as carefully as the wins. The failures are where the real, un-repeatable lessons live. “We tried X, it went nowhere, here’s why” is gold — most people throw it away.
3. Make checking it first an actual rule, not a hope. Before you start something that feels new, scan the list. If it’s already there, you either skip it or write down what’s genuinely different this time. No exceptions — that’s what turns the diary into a brake.
4. Keep it honest. A real “this didn’t work” beats a flattering “we’re always improving.” The list is only useful if it tells you the truth about your own past.

The most expensive mistakes aren’t the new ones — those at least teach you something. The expensive ones are the old mistakes you make twice because the lesson didn’t survive. One file, one sentence at a time, and you stop paying for the same education over and over.

So before you chase the next bright idea, glance back at the ones you already chased. Some of them already told you where the wall is. The only trick is having written it down.