I like to play demo when short on time because players tend to try to hold angles and behave more closely to something like a comp MM game since there's an objective and one life per round. In DM, people tend to run around wildly and not move in ways they'd do so in an objective based mode with no respawns.Do you ever search custom servers - DM/FFA? Best way to keep your aim sharp imo.
You get less frags in per session, but I find it more valuable for reasons I mentioned above.