Why not include some checkboxes along each slider bar at preset intervals?

When i move any of the slider bars, the increments are already pre-set: .5 semitone for pitch control up or down, 4% playback rate change up and 1% down, 2% tempo scaling up and 1% down. Why not put some check boxes along the scales at regular intervals (e.g., +8, 16, 24, 32, etc. for playback rate, and so on), so users can just check a box they estimate they'll want and thus find their optimum settings much faster!