I looked into this and found the 21:36/12 cycle. I haven't tried it yet but from what I read it has been proven. you need a seven day programmable timer and you go 21.36 on and 12 off five times over the 7 days.
You only do it for one or two weeks during flower, like the 5th or 6th week. From the pics I saw It looks like an increase of about 20%
here it is.
21:36/12 flowering set seven day timer:
Day 1 - Sunday, 6:00am til Monday, 3:36am
Day 2 - Monday, 3:36pm til Tuesday, 1:12pm
Day 3 - Wednesday, 1:12am til Wednesday, 10:48pm
Day 4 - Thursday, 10:48am til Friday 8:24am
Day 5 - Friday, 8:24pm til Saturday 6:00pm
I got a timer and Im gonna try it next round.