I think they are pointless. I like to do the real thing instead. It's easy to shoot a bow anywhere and that's the best practice IMO. You can shoot in the back yard, garage, spare room etc...the distance really doesn’t matter if you are shooting to build strength. And you get other benefits like muscle memory, building strength, getting a better anchor point, seeing the target, etc from the real thing. If you are having trouble shooting the bow drop the bow weight down instead of looking at alternatives to build strength until it’s comfortable.