Indoors plant in smallest container and then up pot to the next largest. Repeat until in final container. For sturdiest and fastest vegetative growth .yeah I guess the biggest factor is how much perlite I'm going to mix into my FFOF. Like you said there are a lot of variables where one size fits all doesn't work (some plants are slow in veg..yada yada) Guess I was just looking for a generalization like the gallon per foot rule of thumb....but its never that simple in my world! I feel like my pots are too big for my current grow and I will shortly be able to tell once I harvest what the rootball looks like and I guess I can go from there...