This may not be a perfect schedule (chart below) but if someone could be this consistent in controlling nutes, temperature, humidity, water conditions etc. then I suppose one could reach an ideal yield for a given set of genetics. I try to mimic this schedule and each of my last several cycles have been more and more productive.
Do you grow from clones that have been sorted for the best characteristics (phenotype)? Have you done some mono-culture grows so you can dial in the conditions for a given strain? The problem I have with clones is:
1. Did the supplier of the clones sort for best genetics or do they just pump out as many cuttings as they can?
2. Are the clones actually the strain they say they are?
3. Generally speaking what are the quality of the genetics of the clones?
You could buy some seeds from a reliable source, do your own genetic sorting and then make your own clones. If you sort carefully your yields could increase a lot and you would be satisfied that your effort was part of the success. Also, you could do some back-crossing to get a hybrid that expresses a wide range of phenos and then sort them.
Pick a couple of small things to try different from your last grow or pick one major change like going to some form of hydro. Research it, ask questions here and then try to figure it out from there, then measure your results. keep detailed daily notes.
I agree with a previous poster on the idea of trying a DWC (maybe RDWC) grow. Its a big step but it could be quite interesting.