Years ago when I was a working pupil my boss had the mantra “be rough on manes, gentle with tails”, and would happily use a dandy brush on the manes, and then pluck at the stray hairs, to get them short and a bit frizzy.
Manes were kept less than 3″ long (probably more like 2″) so that plaits were short and neat, and very easy to roll/fold.
This is a mantra I stick to, and a mane like this can be plaited in about 15 minutes (it takes me 1 minute per plait!) with elastic bands. Sorry to the purists, but I only use a needle and thread for 3-day events now!