i think after the light it's a combo of how big ur pots are and how long you veg them for. either of the second 2 being off will drasticly reduce your yeild as you could have a clone in a 5 gallon pot but if you only veg her a couple of days you just wasted about 3 gallons of soil where as if you veged the same plant for a month before flowering her she will never get the same yeild same can be said if you veg her to long for the size of pot she is in once she's rootbound she won't yeild much more then she did if she got rootbound right at the end of flowering sometimes yeilding less. that why it's so important to get to know the strain your growing so you can figure out what works best for her in your garden