I think I'm less concerned about the hourly stops on day rides--even long day rides--although they DO make good breaks for both rider and horse.
I'm thinking more in terms of going horse camping where we're out for a couple days riding--or a week, or whatever. Seems like letting them forage a bit more during the day makes more sense on longer trips. I suppose one reason for thinking that is the critters will probably have more trouble eating well in AM and PM when foraging around camp than they do at home where we toss 'em hay or put 'em in a lush pasture to feed.
But then, maybe somedays we'll get lucky and have really good forage in the evening and morning so getting snacks during the day will be less crucial. Maybe.