I have spent more than 30 minutes in (and on by crushing them ;o)) a very uncomfortable tight pair of 6" mules (the shoes are a half or one size too small). Shoeplay (predominantly dipping) and a lot of moaning and groaning (English subtitled). Some feet rubbing, some toe wriggling. When the 30 minutes were over I was unthinkable glad to slip out of those instruments of and put my feet flat on the ground. Nearly pure amazing closeups. Length 10min 49sec.