How are you going to fit 30 busy managers with tight working schedules into a single week? Isn't it quite unrealistic too to think that they will all want to have lessons at different times? Usually, my students preferred lessons in the earling morning, the evening or the occasionally early afternoon on Fridays. In order to be able to give 30 lessons per week, you would also have to have a lot more students than just 30, as many students do not book lessons according to a fixed schedule/on a weekly basis. I fear that having so many individual students would provide considerable difficulties for the teacher in terms of managing their curricula and not losing track of their individual needs. Furthermore, during my work with LD, there was no such a thing as a stable amount of lessons per week. Bookings were made in a highly unpredictable fashion, and monthly teaching income became inpredictable too, as a consequence. All in all then, the calculation of 30 hours per week is a highly hypothetical one.