My Barn Door before and after.  I can't say that I prefer either one. The process of painting the second one definite felt more confident, perhaps because it was the second time doing the same subject, but also "hovering" brush was noticeably more comfortable after the drills.

Some of the drills....

I have never done a sample sheet like this for all of my brushes and found that exercise very valuable.  To see side by side how each brush's mark varies and have it as a future reference too.