First let me say, that whatever works for you is fine with me.
I have 5 kids and never used a stroller by the time they were 3 1/2 to 4 years old. My kids were all very active and could go 60 miles an hour all day. Heck, they had more energy than me! My feet and knees would be killing me at WDW while they were still encouraging me to hurry up. We'd spend all day at the parks and then they'd spend most of the evening at the pool. I was ready to crash when we got back but they always wanted to hit the pools. I don't know how they had the energy. I vaguely remember having tons of energy as a child---I do know I'd ride my bike, jump rope, swim, or roller skate for hours as a kid--but that endless energy vanished when I hit my 30's.
I took my kids to Carlsbad Caverns when the oldest was 8, the twins were barely 5 years old, and I was 5 months pregnant with the fourth child. There are no strollers allowed in the caverns and you walk for about 3 hours, downhill all the way. My kids never got tired but I was ready to call for a stretcher to wheel me out.
My 4th child had asthma so, even though we abandoned the stroller by 4 years old, we just went at his pace. As long as his asthma was under control, he had as much stamina as the rest of the kids and walking all day wasn't a problem for him.
My personal preference is that strollers would be used a litle less at Disney because it is hard to walk when I am surrounded by strollers. But really, it is none of my business. Do what you feel comfortable with.