Like a lot of people said, you're only supposed to stretch warm muscles. I stretch after almost every ride, usually just Ricci's neck and back. When we have a particularly strenuous ride or it's really cold, I stretch her legs too. You have no idea the improvement we've made because of it. I started stretching her neck and it gets easier and easier to get her bend because of it.
I wish I knew more information, like what kind of stretches were being done and so on. I have a really hard time believing the stretches made them worse unless they were stretched too much, like pulling and straining to stretch instead of just stretching. Also, if your horse doesn't like to stretch, he will strain and it won't do him any good. And there's the temperature factor and cold VS warm factor.
I'm a big stretcher, and this is not going to affect the amount of stretching I do with Ricci, lol.
I do carrot stretches with my horse after we ride, her neck always cracks ! But the only reason I've been doing them after, is bc she's such a piglet if I give her treats, so I just do them in her stall & leave her haha.
I wonder if its anything like working out with people..how you shouldnt work the same muscles two days in a row and you need to give muscles, etc time to heal themselves (IE workout or whatever every other day rather than every day)
Maybe that's a stretch, but just a thought.