I don't want to get in a flush vs no flush pissing match, far too many threads dedicated to that. I will say this though flushing is necessary in a lot of instances. I don't know racers methods but I know he knows his stuff.
Few things to consider (my opinion / experience):
Are you using organic or synthetic ferts, synthetic = flush
What is your medium? I've read and or met a lot of organic soil growers and few if any of them flush.
What is your runoff? I pay really close attention to this and I'm a Sunshine #4 grower. I try to get my run off at or below 200ppm before harvest, with SS#4 it tends to hold salt/mineral and run off can get crazy, I had 1 plant at 3k+ a few weeks ago but got it down to a healthier range.
Try both ways, I find I get a lot more crackling and black ash when I don't give a 2 week flush, just did a 5 - 7 day flush on some girls and not happy with the smoke.