BTW edbert,
If there are others that think the way you do, what if there were 19 players in the CT, 10 more logged on, 5 seconds apart, but only saw the 19 and then logged out before the 21st player logged on? If all stayed for 15 minutes, there would be 29 players instead of 19.
Instead of using the number of players as your rule to play or not, why not try a time limit. Play for 15 minutes no matter the number that are logged on. If this would happen, more would show and keep showing.