I will also give a to this swing/ practice. Found the pdf file on the internet last January.
Was home with plenty of time on my hand Feb-May practice the 9-3 swing everyday for an hour then added longer clubs and longer swings for another hour or two.
My best score last January was 89 most of my rounds was 95-105.
End of April I scored 3 rounds under 80. Due to work I stopped the practicing and forgot about the swing type. My score went back up to the high 80's.
Here 3 weeks ago I 'found' the pdf file again started the swing again.
It did not take more than a few days to get back into it.
Scored 81 in pretty poor condition two days ago and am pretty confident I will be under 80 again in shortly.
Special my wedge play has improved which has boosted my confidence. Like other have also stated.