Transmission fluid change is different than a transmission fluid flush

Some people warn against flushes because it might force buildup into components in the transmission

I have done a change on my truck and it only gets about 40% of the total capacity

Any comments or experiences? Wondering if I should continue to do the fluid change every 100k miles or so (2011 f150 6 speed auto does not have a specified interval, actually it specifies never )