I ran a flood and drain SOG for 10 years.
Typically 40-45 plants in a 4x4 tray under a 1k air-cooled HPS. I used 6 inch square plastic pots filled with hydroton or growrocks. I started clones in peat pellets or rapid rooters. Once they were rooted they went into the 6inch pots and vegged for about 2 weeks to establish strong roots. They went into flower about 7-8 inches tall, and finished around 24 inches usually.
Over the years I grew many different varieties with this system and found I had the highest yields with hybrids that grew nice spear shaped colas. With that type of plant I would typically get 30ish premium grams per plant. With lower yielding varieties I averaged about 20g per plant.