Fifty seconds is just shy of a minute — the length you set when sixty seconds is a touch too long but half a minute is not enough. It works for a short reheat, a held pose, a segment of a timed speech, or a quick countdown where you want a little urgency.
Eight rounds of fifty seconds is a little under seven minutes, and the editor takes whatever count you need. Set it once and a series of short stints stays on the clock without resetting between each.
A 45 second timer for a quick task, a presentation slide, a tidy-up countdown, or a plank. Repeats for your chosen rounds.
A 70 second timer — one minute and ten seconds, for when a flat minute is not quite enough. Repeats as many times as you set.