Unfortunately I can't recall where I read or watched this, but I've gained the impression that a single plant has a limit on the amount of THC it can produce, which varies on the type of strain. Something to the effect that after it reaches this point, the more buds on the plant means the less THC each bud will produce. I might have read this while looking for resources on topping or stress techniques.

Is this true, and if it is, is there any resource on this I can cite to show someone else?