We have a climbing rose (Which I shall find out the name of when S-W-K-E returns from cutting firewood) which usually manages to save at least one flower for Christmas day. The bulbs which stay in year on year will find their own level as some multiply by producing a new bulb on top of the old one, and others by producing smaller bulbs around the base of the old one. As for the gardener bloke, I can only assume he takes out a whole section of bed to the required depth, puts in his first layer, covers them over and adds the next layer.
Too much like hard work for me, but this guy is serious. (He has several 
national collections of plants.)