Some people swear by it. I don't. Some guys say you have to make the calls based on the lineman close to the Center. I'm not sure. I think a lot of it is placebo. I think it does work on some plays, but I also think the blocking on some other plays is just terrible. Like most of the power-o plays
Do not use these plays. Someone on defense will bust through every single time unless you use motion. And I hate motioning a WR or TE to a certain spot just to try to get this run play to work because then if you don't do it for your pass plays then you tip the person on defense off that you are running. But if you do it on pass plays you take a receiver out of the passing game. Mehhhh.
I've also given up on toss plays. All the person on D has to do is run way outside and the blockers will ignore them. Then turn back in and make the tackle. So that really leaves dives and counters, off tackle and that's all you can run really.