Max bonus to pupil is the maximum plunder that ure pupil can have as his/her tutor. For example, if ure max bonus to pupil is 20m, ∴ the maximum plunder that ure pupil is gonna get from u is 20m. It grows big when ure pupil bumps u cause u get higher value and the plunder u give also rises
Max bonus to pupil is as what chan said. It's how much at absolutely maximum you contribute to your pupils plunder. However, once your pupil is at max plunder, the rest of the "max bonus to pupil" doesn't kick in, hence why you don't make like 7b a hit if you owned me lol