I’ve never dug a snowhole myself but I used to come across them occasionally in Glencoe during my winter climbing holidays, roomy and comfortable and I found the little niches and shelves and even seats amusing! A friend fell through the roof of one once while descending Stob Corrie nan Beithe in the Coe!
On another occasion we topped the first rise above Loch Achtriochan heading for Bidean nam Bian to be faced suddenly by a three metre high snowman! Just behind it was an igloo, which struck me as a bit cramped and uncomfortable to get into, but one could probably be made quicker than a snowhole as there is less snow to be moved. The trouble with both snowholes and igloos is that you really need to carry a snow shovel to make one, and for a winter overnighter we would already be carrying a lot of gear!