No, in fact NO, it's NOT the way they are pruned - it's the variety. There are CM cultivars that grow no taller than 3' and those that grow to 35' or more. If you REALLY have fallen in love with one of the huge ones, and have a smallish space for it, you MIGHT get away with keeping it multi-trunked, and cutting out about a third or less of the trunks every few years, but you would have MUCH less trouble if you decided that you do like one that will mature at the desired size.

Pruning for shape and health - crossing, broken or wayward branches - on CMs should be done in late Jan. or Feb. If you want to prune out suckers from the trunks or roots, then do that in mid-summer, as they are less likely to resprout then.