To produce the optimum yeild out of 1 plant you need to find the ballance of space, time, light, and nutrients. It takes several grows of one strain done several ways to find the optimum growth for optimum yeild.
It also will matter as to how much vertical space and lighted area you have, and the strain. I have seen some plants that were grown 6' tall but only about 2' in diameter. They had tremendous yeild. Others I have seen grown only about 3-4' high but very bushy and about 3-3.5' in diameter. My partner and I try for this short and bushy type as that seems to yeild very well.
I would recommend as a rule of thumb to allow them to veg until your space is a little less than half full of plants. The vegging time really depends on how you grow them (any type of training) and whether they are from seed or clone. Growing from seed will require more time so that they can get to maturity before flowering. Clones can be flowered as soon as they have a good root system(if you are height limited this is the way to go).
For any given space, you can either set many single stalk, small clones close together to form a sea of green. Or you can set fewer plants in a more spread out position and do a little training to keep them low. Or you can set a minimum of plants with a lot of space between them and train them to become bushes that will mostly take up the growing space.
If all of the conditions for the given growing space are very good from start to harvest you should get about the same amount of yeild out of any of the above examples. It really comes down to what setup works best for you.
If you would like some suggestions, give us all of the details of your grow and you will get all kinds of suggestions. If you would like individual help you can pm me or most of us for individual suggestions