Thanks for the explanation guys. I definitely like around 10 minute DM matches, well usually with good players it's more like 5 minutes 🙂
I used to play on the 40 minute time limit CTF servers and matches would regularly go into overtime and last over an hour. Reducing this to 30 minutes seemed much better and I originally didn't go lower than this because players often leave at game end. These days, there are enough players coming and going that a shorter time limit doesn't seem like it would make a difference to player retention.
I'm hoping more players will join and vote on this before making a final decision but currently 20 minutes seems to be a good change without being too abrupt.
For the future, I'm also considering limiting overtime and allowing a tie plus possibly changing the number of captures required to win depending on map size.