Steven Wonder '06 SYG #4222 'Alfalfa'
Can't explain the discrepancy between your test and mine except when I ran my test, I think it was about 60° outside and I had the TwinTemp and water heater running. That may have been the difference. But, if it took you 45 seconds, then consider that's 45 seconds worth of running water that you are saving from going into the gray tank.
I have also tested it during a cold night (11°) where I left the valve cracked just a hair (the water pump would cycle about every 70 seconds or so). When I checked the rig in the morning, the hot and cold were still flowing well.
2006 SYG # 4222