I do a perpetual scrog, and its starting to kick ass.
3 weeks in the bubble cloner
1 week in cups (20/4 mh 400)
4 weeks of heavy LST in pots (20/4 mh 400)
4 weeks scrog (12/12 HPS 400)
4 weeks scrog (12/12 HPS 600)
Im still fine tuning the veg schedule to fit my screen perfectly. Thats the key. If you dont veg enough to fill youre screen, youre wasting light. If you grown them too big before 12/12, you will quickly run out of room in the screen.
The pic below shows 2 crops that I only vegged for 3 weeks, next crop going in will be vegged for 4 weeks. They're a month apart.