I think teaching to tie at a highline can't be beat. It gives a little yet holds to pressure... it won't break, and they can't hurt themselves if the ground around them is clear.... And I don't think they are as likely to fall down as they are tied hard.
That works in your part of the country but here, there isn't something around to put a highline up with a lot of the time. The cross ties work pretty good most of the time but every once in awhile, one will pitch a regular fit. They fight it out of temper, not out of fear so as long as they aren't in danger, we let them fight.
Tying to a high line is probably the best. But at some point they need to be tied solid, IMO, I go alot of places where a high line is not feasible. I've just wondered when they can be. I realize even a full grown one could hurt themselves.
The first time we did tie Dot we stayed with her for awhile and untied her before anything bad could happen. They all, tho will/do freak for some reason or another.
Becky
Our seven year old gelding started showing at about 5mos. He will stand tied for hours if necessary. He will also sit down to break a rope or halter if he figures he's had enough :) He'll stand tied to the trailer all day at a show and break loose on a hunting trip as soon as you close your eyes. He learned after he grew up that not much holds his 1200lbs if he sets his mind to it. He also learned best not do that in front of dad :)