I've been doing it on and off, but right now I'm doing it everyday.

What I perceive is that my embouchure picks up 'muscle-memory' on how to produce notes without pressure.

Although I'd like a lot of range, it's not something that I work on as a goal in itself, but doing the 20min G certainly makes me sound better and use less effort in playing.

I did a blogpost on the warm-up, and in that post I supply a 20 min. backing track that might make the warm-up a little more fun to play.

The backing track is in E-minor (Bb-instr), and when I play it I play down G-F#-E- up - F#-G-A-Bb-B-C-C#-D-D#-E and then down again, In other words, all chromatic notes except F which is b9 and G# which is maj 3 on E-minor.

This activates the muscles holding the embouchure, and the better you are at holding your chops, the less pressure you need to produce a tone.

In short: I'm all for it :)