Too slow an activation of the hydraulic movements which engage the clutch bands is the same as a person not letting out a manual clutch in a normal fashion... and it causes greatly increased wear of the friction surface...
I can not agree that the continuation of clogging those small holes in the valve body is a positive affect of varnish build up... and what is likely to happen is the small steel balls in that unit get stuck and don't close or open like they should...
You almost talk like the original engineers bored the hole too large... and we should or need to have varnish from old trans fluid to make it work properly...
I vote NOT