[metaxy2]

There are certainly players who could make a much better move given five hours in a highly complex position (not every move--you'd be hitting sleep deprivation by move 3!). It's not unheard of for grandmasters to spend an hour of clock time on one move, and I bet you money that same player would sometimes go to 2 or 3 hours if they weren't on the clock.

As to visualization without pen and paper, the best blindfold players can keep track of a whole board in their mind, and explore variations deeply without losing track of the current state of the board or forgetting about the key variations they found along the way.

It sounds like you're into chess more than me, so I'm sure you know most of this stuff, I'm just noting it for other people in the thread.