There's 1379 questions tagged transit, and 530 questions tagged transit-visas. For what it's worth, there's 124 with both and 56 with transit, transit-visas, and visas. If you add on your citizenship and what country you're interested in, that's your quota of 5 tags used up.
The tag wiki for "transit" mentions the tag "transit-visa", but doesn't give any guidance on when to use which tag, nor does the tag wiki "transit-visa".
Should we discourage the use of the "transit" tag, or at least provide guidance when to use "transit" and when to use "transit-visas"?
This was prompted by Korean transit visa required for Indian? , which was tagged "visas air-travel transit seoul" and is now tagged "visas air-travel indian-citizens transit-visas south-korea".