Thats the only way I do it now. I've use anchors of different kinds, and different types of screws. Now I just silicone them and slap them up. They stay until I take them down. Never had one come off on its own.
I've siliconed signs to all sorts of block and brick walls. It just takes some masking or duct tape to hold them up until the silicone cures. You can cut them off with a piece of steel cable and saw through the silicone when you need to change them.