I really only deep clean a brush if I have ever gotten it used or a brand new brush to help get rid of the animal funk. If you don't have overly hard water and you ensure to rinse very, very thoroughly after each use and then rinse some more...I suspect deep cleaning a brush you use regularly should not be necessary for a very long time. If ever.

But if you really wanted to for whatever reason, I don't suppose there would be any harm done. As long as you do it in a sensible way.