I always diff every single file before commiting. I don't make exceptions, I have caught many mistakes this way.
Since I also commit often, the changesets are small so it is easily and quickly done.
I find it difficult to believe for someone to know of all the changes that were made. I know that not double-checking will lead to mistakes: our company hired subcontractors and we regularly had to remove their debug statements and such from the code (only if we saw them).
In our team we do several things:
- branch early
- branch often
- commit early
- commit often
- push early
- push often
Of course before you can push you have to pull, but our git server will remind us
I was praised for the quality my work and got a raise recently. I will continue to double check every change, every file. "diff" can save you a lot of trouble!