Is there a maximum amount of time at which it cuts off for safety reasons?
From what I have heard about the 670G, part of the reason people hate it is that it can sometimes give so little insulin for extended periods of time (although my understanding is that it will only give no insulin for up to two hours) that people end up extremely high for hours.
My blood sugar starts skyrocketing after about an hour of no insulin, though at times if I’m running low, I do suspend for 30 minutes or an hour. Usually I can’t go longer than that without going super high and/or developing high ketones.