Again, I've not seen it done nor had it done to myself. And I don't want to either. I don't think it's appropriate nor right to spot a full.
I have spotted a barani (by mistake - a child doing front sault decided to stay tucked, and I the way I had her 'wedged' in my hands caused her to turn when she didn't open out), but I would never do that again either. Front saults and back saults are the only two doubles that should ever be spotted whilst being learnt.
Full twists are hard to spot because the arms get twisted after 180* of twist. You're much better off to have them learn by spotting around the room - that way they can go back to the last progression if they have a hard time trying to turn further, they'll always be able to safely spot a 1/2 if they 'bail', and they HAVE to turn late, therefore less chance of getting lost spatially.
Teach them with straight arms to, to placing hands by side. Eliminates so many problems of twisting before rotating and also struggles with wrapping and subsequent shoulder pulling. It's really really easy if you do it correctly from the beginning.
Also, if they cannot confidently do RO-ff-FTB onto mats in the pit, they have no business on doing it on floor. Very few skills on floor should be learnt by spotting. It also makes it a lot easier come competition time or when they get scared. They need to have confidence in themselves from the start (there's a great thread about this).
I have seen a video of Nicole Harris' coach spotting her for a tuck full on tramp, but I do believe she was perfectly capable of doing that herself, as well as the fact that he didn't do anything.