Hi, Timbit ...
Hope all is well with you.
Most SOG growers shoot for four (4) plants per square foot. The idea is to flower early so the plants grow into one main cola. Everything else is cut off of the plant so the light penetration remains good. Usually, these plants will produce 1/4 to 1/2 ounce each. Now, think in terms of 99 plants, all producing one, 12 - 18 inch, single bud of 1/4 to 1/2 ounce.
A good SOG grower is a skilled grower. Usually, he/she grows only one strain at a time, all from very evenly cut cuttings, in order to keep uniformity among the growing plants.
In your case, with your setup, you'd be talking about growing out 21 plants (four per square foot) from one strain ... all from rooted cuttings..
Vi