I've bought a couple of pipe screens, and use them in a few pipes. I use them in all my corncob pipes and a couple others, all the pipes that seem to have a problem with tobacco getting sucked into the shank and blocking the draw. It also helps me to create an artificial air pocket at the bottom of my bowls to also better aid smoking. It works well for some troublesome pipes.
Eventually, I hope to have enough trouble-free pipes to not have to use any that I don't enjoy smoking...