I'd put 2 holes in one block and 2 in another. Avg block is 8"H x 16"L, you're not getting 4 4" conduits thru one block. I'd just as soon not have to use large fire stop bricks to seal the opening or pay a mason to fix the hole.If you had (4) 4" conduits going through a masonry bock wall(existing) would you chop out a "window" or core individual holes. I believe it's usually an opening made with hammer drill. Thanks.