Is there any sort of "standard" for kitting? Even if unevenly followed and/or varying between makers? I find I'm interested in projects that drift away from standard kitting, but there are only so many things you can do within the limitations of what will be on an ANSI 60%, which seems to be the only thing you can safely assume.
There is no base standard when it comes to kitting, but the one I posted below is generally what the average kitting will look like (except for 1.5 function, that isn't common in base at least)
It really depends on the person, but generally a good set will accommodate all of this at the bare minimum (there are some exceptions, I have seen people remove 6.25u bottom row for smaller runs with sp for example)
For extension kits, you generally see stuff like mx hhkb support, r3 and r4 pg dn and up, shinethrough caps that sorta thing. But again that varies among designer, If I ever run a keyset mx hhkb support will probably be in base.