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?

False! Thats like saying grow a plant 1/2 the size you normally would and it will be twice as potent.

yes and some times it all depends on how to take care of it that will give you the best results, now I was reading the food chart that I got when I bought my flowering food from my local hydro store and it says for early flowering and late flowering giving your plant epson salt will help increast the resin production