I noticed exactly what you were talking about and thought it was probably just to keep the FT shooter loose and not overthinking things too much. I'm not sure there's a conclusive answer across the board. Maybe some guys are better concentrating on it for 20 seconds, but FT shooting is mostly about trusting the repetitive motions you've been practicing 200 times a day for the last 10 years. I feel like for a lot of guys (most?) the worst thing they can do is have too long to think about it.