Yes, use them all the time for everything! Have the square and shaped ones, and the ones with half underside in a towelling (sp?) material. I think they're great
I brought one as my horses saddle was slightly tight at the front but i was advised to bring him back inot work first and then get it checked as he would start to change shape.
anyway i got it and realised i needed a bigger girth as my original girth would go nowhere near him with the polypad on. I used a gel pad instead and sold the polypad.
I spose they are handy to have just in case but ideally i would want correctly fitting tack to not need one in the first place but there are some situations you cant help so they would be handy.
I use on under a treeless saddle - its worth remembering though that if you use a polypad under an already tight saddle its just going to make it tighter!
I use them all the time. Even have a lovely blue one for cross country. Find they never slip and are easy to put on without having to fiddle with straps.
One of my horses is a fidgety 17hh which I have to use a Prolite saddle cloth on and I found a polypad is much easier to throw on and then the put the saddle on top.
The only worry I have is that they are quite bulky and it's quite difficult to see how the saddle is actually fitting.
I use them, on one horse, but she is having a new saddle fitted next wed so will stop then. I find that they never slip backwards and are very convienient but sometimes they do pull down on the wither. Had a dressage instructor that used them on everything but with a saddle that fits properly i wouldnt. Good for old horses that need cushioning.
Under a saddle that fits properly, they make it tighter. Used to use one on my cobby, and with my K2 as it didnt move. Wont use one with my CC saddle as just slips, and also makes it too tight. Good if saddle needs adjustments, and would prob use one with a dressage saddle, but not under a CC saddle.