I had the exact same frustrations in my initial veterans draft, as we had many teams which were abandoned by the time the draft kicked off, so it took forever.

I think a good middle ground is the following: if a manager does not sign on to make their pick and the system auto drafts for them, the next time it is their pick the time to make a draft selection before the computer autodrafts for them is set to 15 minutes, unless the manager signs on and unchecks the autodraft button in the meantime. Decreasing this drafting time for abandoned and autodrafting teams from 1 hour to 15 minutes would significantly decrease the amount of time spent by the other managers sitting around doing nothing waiting hour after hour for the computer to make picks, while still allowing time so the draft doesn't go so fast that it's inconvenient for anyone.