Created a task with a 1hr reminder to the task owner's superior after task deadline. When the task got to that stage, it was ignored for weeks as we were just testing and it kept sending email reminders per hour and going back to sit on same task without interrupting the task. In such a case, does the task need to be interrupted?

Yes, if you have a timer boundary event attached to a user task, if the flow out of the boundary comes back into the same user task, you need to set it to interrupt. That way, when the timer hits, it will cancel the in-progress user task, then create a new one. The way you had it set up with not interrupt will leave the initial user task then create a new one each hour. The assignee would then have 2 after the first hour. If you have the timer set to repeat, now both user tasks are on the clock. After an hour, the timer hits for both and 2 more get created. Now you've got 4 user tasks and repeating timers... Exponential growth is no good and would definitely cause this behavior after a few days.