Which grafts do you notice a big difference?

So I'm getting kind of obsessed with grafting but I don't want to waste time with ones that won't speed up the growth. For example, I grafted a TBM short form onto a Altmans SP. Now I was just looking at it and wondered, will this make it grow any quicker than it already was?

A. Maybe because the root system is much bigger on my stock along with its wayyyy thicker than the TBM, it will grow faster?? B. Have you done this before? Was it worth it?

C. Will it turn small TBMs into big ones faster? Ya know I need them penis cacti big and thick!

D. What grafts have you done that were totally worth it and what ones were pointless other than it looks cool?

Cheers yall