I am assuming that you are figuring this off your own medical needs. It is a given that once you find the strain(or strains) that works for you, then you just clone them so that you can have faster turn-over and solid predictable growth patterns and yields. But another factor to consider is your space for growing. This is a very strong deciding factor in how you grow as well as how much you grow.
Ideally, for maximizing your yield potential over a given period of time, you should look at a 3 stage grow. That being a dedicated flower space, veg space, and cloning space. These spaces don't have to be big to get the level of meds for personal needs. There are a couple ways that you can do this as well. You can do fewer, larger grows for larger yields at a time. These larger yields can then carry you longer between grows. Or you can do a "perpetual" grow where you are growing more smaller plants that are spaced in their harvest times. This can be varied as well(depending on the amount off grow space) so that you can have medium sized plants giving medium yields, but then they can be time spaced so that you are harvesting a portion of the grow every week, every 2 weeks, 3weeks, or 4 weeks.
I know that in a 4'x4' flower tent, I can consistently yield (with 4 medium-large plants) 20oz per harvest. That is with a typical 9week hybrid strain. If you have dedicated flower and veg spaces available(and working with clones), you can remove the veg times from the equation entirely and plan solely around the flower times. You can then either do single runs each time and yield the full 20+/- oz every 9wks, or you can split the space in half and yield 10ish oz every 4.5 weeks. I personally wouldn't recommend splitting a 4x4 tent into 4 separate time grows because to keep them from interfering with each other, you would have to grow the plants smaller (more plants in a SOG type) and would potentially lose yield.
However, the full size grow would be yielding 2x as much as you need, so you could do the smaller plants in a 4wk harvest for half the 4x4 space, or the same smaller plants split into 4 grows(quarter the space) on a 2 week harvest schedule and still yield enough to easily cover your needs. I wouldn't recommend doing a 2 week harvest myself because growing and harvesting would become your whole life. I did this on a larger scale with a 3 week cycle and I couldn't go anywhere or do anything because I was glued to the care and upkeep of growing on that level. It became more than a full time job.
If I ever go back to growing at that level, I would only do a 4week cycle as less was daunting. Even with my small personal grow now, I find myself very busy with the care of the plants, and the planning and setting up for the next grow with new clones and vegging plants to stay on schedule so to not lose valuable flowering time.
:doh: There are mathematical equations for figuring your grow but there are so many ways to skin this cat. So the equations are different depending on multiple factors of space, your amount of free time, the amount of money that you can sink into this project, and the multitude of methods that you can employ. 
