You shave tails? I was taught to never EVER shave a tail unless you were doing show cob classes (that's the coloured cobs, as opposed to welshies). For everything else, you PULL a tail. Or plait.

In showing classes, it's only really correct to hog/roach the mane of a show cob. Natives and arabs you leave natural and everything else you plait, as a general rule. Dressage is usualyl plaited and/or pulled, but I don't think anyone would be marked down for deviating. But for any other kind of performance class (showjumping, XC etc, we don't have hunters) you can choose whatever you want.