Perhaps you missed my point.
Many -many- divers that are practicing and preparing for a DIR-F class skip some of the steps that you will actually learn in the class. One of them... making sure your harness is fitted correctly. If your harness isn't fitted correctly, you can practice and stretch and crane your head and try and try and try, just to find after you step back and properly fit your harness and properly position your tank on that properly fitted harness.... you just wasted a ton of in-water time trying to fix something that isn't necessarily broken.