The max drift is a magic tool for working out headings. If still not convinced, check out a few examples on a whizz wheel and you'll find your within a few degrees.
anyway, i found that hardest part of teaching this method in the air is peoples lack of mental capacity to work out how what the angle between the track and wind. and hence how much max drift to apply on diversions or replans. it's much easier to use the DI (or OBS if available) and imagine an arrow for the wind. this will help you to 'see' the angle between the track and wind.