I'm not going to start test-deleting, because whatever breaks probably won't make itself known straight away. But surely I only need the latest version?

You'd be surprised how poorly programmed some games are; having for example a firm version requirement of a certain library 4.10 and only 4.10.

Well, no, if you don’t use them for any of your products. I don’t see why it’s an issue though, I have the complete pack and it’s one of the first things I install and then forget about. Loads of things link to those, and some specific versions of them, so something will stop working for you eventually if you don’t have them.

Visual C++ 2005, 2008, 2010, 2012 and 2013 all don't overlap so you do need them all. The 2015-2019 installer though seems to be continuously updated, so no separate 2015, 2017, 2019, etc. You also need x86 and x64 versions even if you're running 64-bit OS.