Twenty-five minutes is the length the Pomodoro technique made famous — a focus sprint long enough to make real progress on a task, short enough that you can promise yourself the finish and mean it. Away from a desk it is just as much a cooking or baking stage, a podcast or lecture segment, or a time-box on a chore you would rather not let sprawl toward thirty.
On its own the twenty-five minutes counts straight down with no break; set a round count in the editor for consecutive sprints. If it is the breaks you are really after, though, a timer that schedules the rest tends to beat a flat repeat.
A 24 minute timer — about a sitcom with the ads cut out, or one long focus block. Repeats as many times as you set.
A 30 minute timer for cooking, a nap, a TV episode, study, or a parking meter. Repeats as many times as you set.