My simplest comment is that my classes taught by male teachers tend to be more physically challenging than my classes taught by female teachers, even when the class “level” on the schedule is the same. This might be sexist of me. It might be because what is physically challenging for me personally is not the same as what is physically challenging for most men – perhaps my man teachers are not making classes hard objectively, but rather the sequences and poses they choose are just hard for me.
However I suspect there is a different cause:
I think men are less culturally conditioned to please everyone. I wonder if, when female teachers see students struggling, or tired, they are tempted to choose easier, slower sequences, and more basic poses, to make students feel more confident. I think male teachers are less likely to feel this pressure to please students. Perhaps if the class is hard and the teacher is female, students tend to think the teacher did something wrong, whereas if the class is hard and the teacher is male, students tend to think they need to work harder (or something).