M2 - 10 minutes
This weekend I shot several targets with 30 second stacks for 10 or 60 minutes. Three telescopes, three ASIAir, merged into one image via the OBS live software and it worked great.
1) RASA11 + ASI2600 mc + Duo-Band Filter
2) Celestron C8hd + ASI533mm
3) A small telescope with a focal length of 162 + ASI432mm