I have the same oil/water separator attached to my Yong Heng compressor. I do direct fills to my PCP's so I don't run my compressor for more than 2 minutes at a time, which is usually enough to fill or top up any PCP I own. I'm not sure of your situation, but I periodically check both the Yong Heng filter as well as the Tuxing filter. I have only replaced the Yong Heng filter once after about 15 minutes of run time for the compressor due to noting just a little oil on one side of the filter, but no water or oil on the end furthest away from the compressor. I have checked my Tuxing filters about every 10 minutes of run time and have yet to see any oil or water deposits.
My guess is that the longer you run the compressor, the more moisture develops within the compressor and ultimately ends up going to the filters. I have yet to see any water or feel any significant moisture when I bleed the system before turning off the power to the compressor.
As far as re-using them, I tried cleaning the Yong Heng filter with soap/water and it just lost its shape and density in the center so I just replaced it with an extra one they provided and bought a 100 pack of filters from ebay to have as spares for the future. I'd say replace your filters once they show signs of wear/oil/water. Best case is you just air dry them and re-insert them once dry. Hope this helps.