Yes it all depends on the size of the plants. If your starting from seed the dual size clips work good.
http://www.johnnyseeds.com/p-6414-sp...ting-clip.aspx
I find it easier to use cuttings to graft (easier to match sizes imo). No limits to how many grafts you can put on 1 plant which is the best part of the whole grafting adventure for me then i will replace the root stock later with something that has some Disease tolerance if i decide to go that route. Being able to grow multiple varieties grafts allows me to enjoy more choices with less space. If you want I can send you 5 dual size grafting clips if you like for practice before you decide to order online.
Right now i got just about 40+ grafts with all of them being different variety combinations (2-4 varieties per plant) of what i want to grow for next year. Eventually i will replace the root stock with something more Disease tolerant when it comes down to planting time.