Posted: 20/08/2014 at 22:04
Never heard that one, OL and to be honest can't imagine what it's based on.
It is advisable to note the potential spread of each rose before you order, so you can avoid overcrowding. Overcrowding prevents free circulation of air between plants and thus causes diseases. Also to this end, when pruning keep the centre of the bush open, ie prune to a kind of wine glass shape.
Also, individual beds of one variety look much better than mixed beds.