A 10 point hang doesn’t even require an active mechanism. An inverted wedge, a moderately fast drivetrain, and the right center of mass will do the trick.
For teams that can 10 point hang, the average should only be 3-5 seconds. But I don’t think it will be, because asking teams to build a mechanism robust enough to lift a 120 lb robot is still a challenge (not to pick on the design mentioned here too much, but a 1 foot cylinder with a hook being rammed into a pole is a decent lever arm that teams may not have braced all that well). I think a lot of mechanisms will jam, miss, be damaged beyond repair, etc. and that’s ignoring lining up correctly (what if the hook spins and faces the wrong way?). I see the average being more like 20, with at least a third of attempts failing.
I’m taking a pessimistic view here, and I wish 95% of teams could at least 10 point hang because all alliances scoring 30+ a match would make for a really exciting competition. I’ve seen too many 0-0 or 0-2 matches to think it will happen though.
The first thing that will prevent 10-point hangs is, in my guess, robots that are sufficiently tall that very small deviations in their center-of-gravity will torque the robot just enough so that it touches the ground while hanging from the lowest bar.
If the hooking device is directly above the robot’s center of gravity, a hook with either a sufficiently fat pneumatic cylinder or a ratcheting winch should be sufficient for a ten-pointer, and very fast.