I have found that as cycling fitness changes over time and the distances undertaken also change, sensitivity to different measurements in bike fit also change. From a comfort point of view, stem length has little effect and nether does saddle heigth. I get a bit more power with the saddle forward several cm but that puts extra weight on my hands which is uncomfortable. What seems to make the greatest difference fo me is saddle tilt. The tinyist bit of tilt is sometimes felt right away but more frequently after 30 miles or so. In the end, it all seems to be interdependent so that one measurement effect all the others. Just recently, for the first time ever, I dropped the bar below the saddle one cm and this is the most comfortable position I've experienced 'till now. This was totally unexpected and was done to explore all options, even stupid ones.