If I am by myself and I know I won't be doing anything but brewing that day, yes, if I'm on the ball and keeping up with the cleaning (so I don't have to do it after) I'll start during the mash. If not, I'll wait till the boil and leave the cleaning till the next day.
3 or 4 fingers of scotch (Glenfidditch is perfect for this) during the boil, pull out whatever book I am reading at the time (for the nerds out there book 9 of the Malazan series) and just sit back and chill (literally now that its basically winter in Wisconsin.
When I was first starting out, and when other people are around, I will not drink, at least the most I will have during the course of 4 hours is (maybe) 2 lower gravity beers total. I would get in deep doody if SWMBO was around and I was half in the bag and dumped 5 gallons of boiling wort all over the place.