An hour is the unit the day is built from, and a visible countdown makes it concrete: a fitness class or gym session, a stage of slow-cooking or roasting, the hour on a parking meter you would rather not overrun, or a deep-work block you protect from interruptions. Sixty minutes is easy to set and easy to forget — the display keeps it in view from across the room.
For consecutive hours — a double-length session, or work-then-review blocks — name a number of rounds in the editor and each hour counts down and renews, so a multi-hour stint runs without a reset.
A 30 minute timer for cooking, a nap, a TV episode, study, or a parking meter. Repeats as many times as you set.
A 90 minute timer — a football match, a movie, or one full sleep cycle. Repeats if you need it to.