That would be a pretty normal amount of prep for a horse, particularly at indoors. Remember there is no turnout, and by the Maclay there’s been no turnout for most of them for over 6 weeks. Warmup when you are on for the class is 10 minutes basically, so there also needs to be some rider prep.
Totally different sport, but forever a day ago when I groomed upper level eventers, 2 hours of lunging and riding before the pro got on to school the horse would be a normal day. This was also in the days of long format, I’m not sure if anyone still does that today.
I completely agree 2 hours of going round and round and round the warm-up continuously would be insane (though I’ve heard stories of it). But I think 2 hours is a fair limit for someone who might take their horse out multiple times a day to stretch their legs in lieu of turnout. Some show grounds don’t even have a decent hand walking areas so lunging or riding it is.
Except Hope said the same thing was going on in the jumper ring and Armand believes it only happens to equitation horses.