Not necessarily. If it did that, it will skip a lot of things you do after ending a long task.
I use one I made myself, and it is set to ask every 13 minutes - the largest prime below 15. Being a prime means it's unlikely to align to any real-world task boundaries, and it's also coprime to 60, so it won't keep asking at the same times every hour.
(Timer like this is actually a nice use case for a smartwatch, along with pomodoro timers. It removes friction from the UX, makes the whole thing less distracting, and allows it to be monitor almost all tasks during the day.)
I use one I made myself, and it is set to ask every 13 minutes - the largest prime below 15. Being a prime means it's unlikely to align to any real-world task boundaries, and it's also coprime to 60, so it won't keep asking at the same times every hour.
(Timer like this is actually a nice use case for a smartwatch, along with pomodoro timers. It removes friction from the UX, makes the whole thing less distracting, and allows it to be monitor almost all tasks during the day.)
EDIT: See https://news.ycombinator.com/item?id=20625346 for details.