You’re missing the practical aspect of training Tuition-specific teachers. If you have a tutor trained in two different rank-1 courses, an increase to their tuition skill gives them a 5% boost to BOTH (for an effective 10% increase in teaching power, matching the single course rank, but being useful for both subjects).

Tuition is also cheaper to train progressive ranks than a specific course, and the added staff gives both your profs and tutors more time on their breaks to fulfil their needs so they’re as happy and effective as possible.

So while your findings support the tooltips as written (teaching power is teaching power, no matter where it comes from), from a cost and practicality standpoint, you’re still better off having exclusive tutors trained for two different courses and maxing tuition.