Yes, it holds true for grafts.

Beyond that a 3-in-1 tree or similar multi-grafts are usually a bit on the challenging side to manage. One variety is always stronger than the others and, in many cases, takes over.

You might want to choose a smaller tree with thinner branches which can be tied down more easily. Knowing the apple cultivars and hopefully the late ripening ones are grafted on the very top...when ripe not falling on the late apples below, some nurseries haven't thought of it yet.

IMO a multi grafted apple on anything other than a dwarf root stock is basically a sales gimmick. Terrible crotch angles are almost a guarantee, and all you end up with is a tree that is 90% one variety and a single branch (if they dont die out) of the other side grafted varieties. You are in a far better situation to buy a variety you like and then graft the other varieties onto the that tree once it is well established.

Ehh it sounds like I might be better off doing a high density, 2 trees in one hole kind of deal. My yard is getting pretty limited on horizontal ground space though, been looking into the tall narrow central-leader apple tree thing (as seen on another thread I made recently).

I'm not huge on apples, but the new bare roots were blooming at the nursery and very attractive, thus the urge to impulse buy was strong haha. I might just put in another pluot or something else in to simplify things. Whatever I plant is going to be right on the outer edge of a large bushy tangerine tree. Maybe an apricot to go with my new flavor delight.