Yes, on my regular 400 thread count 100% cotton ones I do. The flat ones come out so wrinkled on the sides that they would be a good 2-3 inches shorter just because they wrinkle in on themselves (accordion style) where the side seams are. And where the top (head part) is, it's so wrinkled and misshapen, I have to iron it so it lays flat. It's awful!
I feel like I'm living back in my Grandma's days where you had to iron everything because that's what you did back then. My flat sheets of the ones that are not Egyptian Cotton are the only ones I do that with, but it's still a fat PITA because they're so wide that the ends get wrinkled (just from laying on the ground, not accordioning like before) by the time I'm completely finished. If I'm going to iron something, I would prefer it to be completely smooth from the ironing, dangit!
I'm totally investing in like 6 Egyptian Cotton LE sheets so I can "donate" the others to people who don't care or who will iron them. Like my mom. She'll iron them. She still iron's everything (okay, not everything, but my dad's work pants...Dockers...and the lapels of his polo shirts so they don't roll up, Church shirts...and her...well everything else I just toss in the dryer for 10 minutes to get the wrinkles out). I'm sure you can get the gist of how often my mom irons. My ironing board is used as a desk unless I'm ironing my current sheet's. Or maybe, MAYBE a pair of khaki pants for work. Basically, once in a very blue moon. I hates the iron.