If only...
On my recent SEA-PVR flight I counted ~45 Y pax using the F WC. Yes, after the first 20 or so pax I kept my sanity in 4D by counting. This included one or two regularly in a holding pattern by the flight deck door. At one point a F pax went to the back due to not wanting to fight the crowd. I had to push back Y pax who were standing by my row and holding on to my seat back. My critique to the F FA was met with a feeble announcement about 45 minutes prior to landing to use the WC in one's cabin. Thankfully my return flight was stellar with one of the most professional FAs I've had the pleasure to fly with and no unreasonable F WC use.