Mine gets lots of hard feed, but always has access to haylage or hay (or grass, as is turned out for 14-16 hours a day). If he finished his ration, I would make sure I left much more for him the next day. As it is he gets 2 large stuffed haynets, and usualy leaves half to 1/3rd of each.
He used to be on fibre only (with his suppliments), but RI recommended his current diet of competition mix and sugar beet to up his energy levels, as he is rather lazy, particularly in the school. He doesnt get fizzy, and isn't a very good doer, though looks great just now! Oh, I realy notice the difference in his coat when he gets oil as well - just a swig at night.