Here is a related question.

Why does the fluid level need to be submerging the valve body? Does the valve body aerate the fluid if the level is below that? Such as at high rpm and shifting, not driving around the pits. Maybe the servos aerating the fluid if their bottom is not submerged (normal leakage)?

The reason I ask is that I notice my race trans has issues if the fluid gets a little low. And it has a super deep pan with a 2" filter extension (with o-ring seal against the valve body). So air isn't getting in the filter.