Mover is really intended for idle time. There is simply no way to move from cache to the slower array as fast as you can write to cache. Doesn't matter how often you schedule mover, and if mover is trying to run at the same time as things are writing to your server, it is just going to be competing for those resources.
Our hardware is very fast these days, but our data is also very large, so things seem to take as long as they always did.