Low sens is for people who want instant results. The lower they go, the less they can potentially do. The sens ends up defining them as it prevents them playing certain games, certain roles, certain weapons, etc.
You also got to factor in hardware and peripheral choice, physical strain, RSI, energy requirements, sensitivity spread, etc.
Light mice and large mouse pads become a necessity. Muscles start to accumulate fatigue and stress due to no downtime in excessive movement. Playtime may decrease because one requires more energy to feel like playing. The holding of the mouse and style of motion stays the same past a certain point, making any sensitivity slower than that point a possibility. This causes a constant change of sensitivity, within a pretty large spread. Things like that.
Stick with a comfortable sens that you feel can accomplish anything given enough time practicing with it. With 4 years as a time frame, I wouldn't even consider falling into the low sens trap.