In Ted Hooper's book 'Guide to Bees and Honey' which is good in my view, he gives a fairly long explanation about brood spreading to grow the size of the stock in spring; in simple terms a frame with a small amount of brood from the outside of the brood-nest is put in the middle of the brood-nest, encouraging the queen to lay on it. I guess that if there are plenty of bees and the colony would otherwise grow slowly, it might encourage the colony to grow faster than it would otherwise do. Conversely, a colony that's covering the brood thinly because it's already expanding as fast as it can would struggle to keep all the brood warm so brood-spreading might be counter-productive.
Does anyone spread the brood or just leave the bees to do what bees do?
Does anyone spread the brood or just leave the bees to do what bees do?
May your bees read the same books as you do.