I am another who loads primarily on a single stage these days, by choice. When I really need a bunch of ammo I still use the old progressive, but that just doesn't come up much any more.
With the single stage, I always work in batches, and most of it is kind of brainless. You really don't have to have laser-sharp focus to resize or flare. I pay more attention when priming - I always wear glasses and make sure the case mouth is pointed away from me - and of course charging and seating do get my full attention. I've whiled away many pleasant hours, though, performing the more basic chores of handloading while listening to music or watching TV - and even enjoying a good glass of whiskey or gin - and I doubt there is any reasonable argument against it.