We use the categories feature for triggers pretty heavily. They are massively helpful looking at segments of different lines of business. In addition to other categories, the categories doing the biggest lifting are assignment, communications, and then line-specific triggers.
We also rely on the sandbox to test changes before deploying to live. Although the triggers get refreshed when you spin up a new sandbox, they don't carry over the respective categories and they all get lumped into one.
It would be very helpful to improve the parity between instances by carrying over the categories when creating a new sandbox - not only for ease of use, but also so that any admin can avoid triggers that might be mistaken for similar ones that would otherwise be under a different category in live.
