Rarely. I remember once, over a decade ago, when I had severe insomnia (76 hours awake in one go), I spent the best part of 26 hours painting Mutant Chronicles miniatures with breaks for only drink, food, and bladder relief. Physically draining, but I got my Centurions, Necromutants and Undead Legionnaires all done, as well as some I promised to do for a friend of mine.
But as soon as I come back from my holiday in the States, I fully intend to do a couple days' worth of solid customising!