What can I really expect to see?

This is a noob question i know so im sorry about that but I read people saying you will not get more then a 6-7 oz off of 3 plants when growing indoors but a good amount of the seeds ive looked at say they on average yield 300-450g . I guess my question would be is what they're saying they will yield is including the whole plant or are some people not lucky enough or don't do enough to get that many grams per plant indoors?

My setup is going to be:
Snow white on a Stealth Hydro setup with the Duel Spec 2 lights

when the seed company puts those numbers, it means that a person doing SOG, or SCROG can get that much per meter squared. so in a 3 ft X 3 ft space, tightly packed with plants, and the perfect environment, will get that 300-400 grams.

That makes much more sense thank you!

no problem man.... happy growing!