Things broken on purpose

Latency budgets work better than latency targets. Targets are aspirational. Budgets force you to delete features when you go over.

Most of the trouble I see in production comes from boundary cases someone promised would never happen. The code is fine. The plan is fine. The promise is what ages badly.

I write smaller commits than I used to. The commits are uglier in isolation and much easier to read in sequence.

I split a 4000-line file into 12 smaller ones this week. The smaller files weren't actually easier to understand. The 4000-line file was a problem of structure, not of length.

When a system surprises me, my first instinct used to be to fix the surprise. Now my first instinct is to figure out which mental model of mine was wrong, and update that.

I used to add a layer of abstraction the first time I saw a pattern repeat. Now I wait for the third. The waiting is uncomfortable, but the abstractions that survive that wait tend to last.