Elfie, that's the concept they use here too. I haven't seen them do it with windows but for sure they do it with cabling and wiring channels. First they make a nice straight wall of block and then they chip away the part for the wiring channel and then patch it when it is finished. Almost anything you need to have done here involves chipping out concrete and patching it again. When I wanted new hammock hooks, chip a hole, put in the receptor and then fill it with concrete. Also, hanging pictures or heavy mirrors, moving an electrical outlet, they just don't see breaking a hole in the wall to be a big deal. I had to get over that, it seemed extreme to me. It also means that almost any job creates a huge amount of fine grey dust which gets into everything.
