While playing with exposures and development times, you are playing with contrast and grain only! Are these two, contrast and grain, the single variables defining what you see in your head? Somebody mentioned the film bringing its specific curve, etc. I would add the lens, with its specific MTF. Lenses can give you differences as big as changing between brands of film. But most of all counts the light! – I see now, "mhv" mentioned it too, while I was writing these. I cannot understand how would you shoot 8-10 rolls on the same light – and not any light, but the one you mostly love. Finally, there also are the filters: these can dramatically change the mood of the picture.
To resume, I would say there are two classes of factors influencing the final print’s aesthetics: in the first class I would put the artistic factors, and in the second class I would put the technical ones. But don’t ask me, which are where? I am still looking for answers here. But, for example, the light, the lens, and the filters I include for sure to the artistic factors. Exposure and development compensation belong IMO to the technical ones. But I don’t know yet where to put the films and the developers – I recline to go for the artistic class again. In fact, these are personal choices, there is no rule to go for, and it is very good to be so.
Finally, there also is a question of what kind of experiments you are doing. The systematic ones (the real experiments) are for confirmation goals, while exploration experiments (which more rigorously are called experiences) are for discoveries. Both, experiments and experiences, have their role at a certain time. What I understand is that you did your experiences (discoveries) in the past year, and now you moved to experiments (confirmations). I think you are on the good way, from this point of view. Just do not forget: once the present experiments ended, play again with new experiences.
Personally, I think there is also a link, on one side between experiences (discoveries) and the artistic class of factors, and on the other side between experiments (confirmations) and the technical class of factors. What I mean, is that during experiences your variables are the artistic factors, while during experiments the variables you are playing with are the technical ones.
With these clarifications (helping you, I hope, to position yourself and to make choices), I wish you good luck!