Why my CI got 4 minutes faster

Caches solve a problem and create three new ones: invalidation, observability, and the slow drift between what the cache thinks is true and what the source thinks is true.

The team I learned the most from didn't have great tools. They had a great habit of reading each other's pull requests in full, including the parts that weren't theirs.

If a config file has more than a dozen options, half of them aren't being used. The other half are being used in ways the original author didn't predict.

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

The fastest debugging trick I've learned is to write out, in one sentence, what the system is supposed to be doing. Half the time I notice the bug while writing the sentence.