“If you are a programmer, try to find an answer by reading the source code”
This is basically a superpower at any large tech co if only because few people do it, even though we’re literally all capable of it. When I inherit or start interfacing with a new service, the first thing I do is checkout the code and peruse through it. Even just 30-45 minutes, for an experienced engineer, is enough to get a feel for the layout of things. Then when you have a question about “How does X service handle Y scenario” you can just go read the code and know the answer exactly.
I can’t tell you how many times I’ve had the answer to a question and get something like “dang rco8786 how do you know so much about how everything works” and invariably my answer is just “I read the code”.