When developing improvents to your drying schedules it is best to change as few parameters as possible. This is similar to the idea of setting singular goals. By studying the effect of lowering only the temperature, it is fairly easy to see the exact change. Whereas studying a change in the temperature, relative humidity and air flow will not provide a similarly clear picture, since three factors were changed and it may be unclear which ones helped improve the drying quality and which ones may have hurt the drying quality.
Let's imagine an example where we would like to dry a load of maple with a lighter color result than the schedules used in the past. It could be argued that by lowering both the temperature and the relative humidity setting you would get a brighter color. However, the lessons from an experiment where both the temperature and relative humidity is reduced will not be as educational as two test runs (one with lower temperature and one with lower relative humidity). By making two test runs you will learn what each change accomplishes.
Remember that you must have an accurate method establishing a benchmark to meassure you improvements.
Learn about how adjustments in temperature, relative humidity, and air flow changes drying rate of the lumber.