CO2 in a closet or small area

I was watching SeeMoreBuds Vol.3,
and one of the gardeners used dry ice in his grow rooms to let off CO2.

Is this necessary? Does it help?

I figured in a closet setup CO2 must come at a minimal. Should it be recreated?

Maybe dry ice durring flowering would affect the plant and make the buds bigger. I think the extra CO2 would stimulate extra growth durring flowering. Just need to figure out how much dry ice to use.

I think ya need to go through a lot. Its gettin the right amount of water drippin on the dry ice @ the right rate. Honestly, just get a regulator, tank, and timer. IMHO, seemore buds leaves A LOT to be desired. Misinformation, not enuf info, just kinda basic guides that really CAN hurt 1 more than help.
BTW, yes, Co2 DOES help, it increases bud size from 10%-100%, makes yer girls MUCH more heat resistant, and is not always necessary.