I find it kind of annoying, it's how Marvel set up Secret Invaison and in both cases it boils down to "Batman/Superman/X-Men/etc you're selling well so we'll put your tie-in in a seperate mini-series that doesn't really effect you at all but Booster Gold/Incredible Hercules/etc you're doing so well so this will happen in your main book in hopes people will pick up a new book because we put a logo and a Skrull/Black Lantern on the cover".