I realized that you actually get more Karma by not collecting. Every time you collect the timer resets to 6 hours. So if you had one that would be ready in 10 seconds you'd lose it and it would be another 5 minutes before you got the one you would have had in 10 seconds.
At least I think that's what happened. I was supposed to need about 4 more Karma after my last round of sending characters to earn Karma. I was collecting from the fountain over the 4 hour period. When the characters paid out I was like 17 short instead of 4.