My wife always reminds me when I ask her to come join me for a short ride, "That I don't know what a short ride is"
Weekday evenings a ride is a couple of hours. If the horses are out of shape, We walk with some trotting, If they have been worked in the past few weeks, we up the speed and do more trotting.
I've done lots of Competitive Trail Rides were we rode 50 miles over the Sat/Sun. And I've done a few endurance rides where 50 miles in 5-6 hours was the norm. So a fit horse can cover a lot of ground in a day. I know the biologist I've talked to say it is very common for the wild Mustangs here in Utah to cover 20 miles every day as they search for food and water.
They hold a Outlaw endurance ride every fall in Southern Utah. They ride the old Outlaw trail and do 5 days of 50 miles each day for 250 miles total. If you ride the same horse for all 5 days, They call you an Outlaw, If you change horses on some days, They call you a pinkerton A throw back to the old detectives that chased the wild bunch. The point is that if the horse in in shape and you give it enough calories for energy. It can work multiple days in row . We work our horses pretty hard during the Elk hunts. But I usually give them every 3rd or 4th day off to recover.
I often ride into the mountain and remote areas of Utah and Wyoming. Since we have made the effort to get to some remote spot, we are going to ride all day. I allow the horses to graze anytime we stop. At lunch, I put on hobbles and let the freely graze while we eat lunch. It's not fair to ask the horse to travel 20 miles up and down mountains and not give them calories to do the work.
Horses hobbled at lunch
If you are going to start riding for longer distances you should learn some basics of taking your horse's biometrics. Learn how to take his Pulse and Respiration and know what are his normal vitals and when he is showing stress. Learn to check his hydration, a quick check of his capillary refill by pressing his gum tissue or a Skin Pinch, how fast does his juglar fill if you press on that. What are his gut sounds. And what are normal gut sounds. You should be able to know what state your horses is in and if he has become stressed.
I let my horses drink any chance they get. In the desert we don't always have running water. It is often water trapped in Indian Bathtubs in the rocks
I always have matches to start a fire. I keep a space blanket. Too many hikers have died from Hypothermia when a hot july afternoon turned into a violent thunderstorm and they got wet and the temps dropped. At least with a fire and reflective blanket you can stay warm. My cantle pack always has several granola bars, and hard tack candies, Things that keep forever with out spoiling and bottles of water. The farther that I will travel away from my truck, The more supplies I load into the cantle bag and the better chance I will have a jacket or slicker tied behind the cantle.
I also almost always carry a pistol. We have had to put horses down in the back country, miles from help. We hope that it rarely happens but when it does, a pistol makes rough job easier.
In the trailer I keep basic farrier tools to trim up a horse, basic horse first aid kit, to clean, numb and stitch up a cut.