depends:
1) how long you veg them for
2) if you FIM / Top them (which also increases veg time)
3) indoor vs outdoor
4) if indoor then dirt vs hydro (dirt gives better taste whereas hydro gives more quantity)
5) if indoor how powerful your lights are... both veg and bloom lights. (more powerful = more yield but also = more cost)
among other things. You may wonder why someone might not want a system that optimizes yield.... this is because there are other limiting factors such as space (cant grow plants too big in small places), time (dont want to wait 4-6 months), legal issues (how much is considered a misdameanor vs Felony), and smell. Smell is one of the most common ways of getting caught (ie: a neighbor smells it and snitches on you to the popos); smaller plants smell less when blooming but also yield less.
So there are few things to consider.
-T