Transmission service beyond 100k

I searched and could not find any relevant posts. I flushed my tranny at 85k when I bought it (blackish then) - they did it twice to get the color right.

I an wondering when should I do it again - also, drain & fill Vs flush?

@alawat82 previously posted saying s/he likes to drain & fill every 30k - is there a time limit too - with pandemic it's not being driven much?

Here is some good info too - unsure if he refers to flush or not:
" transmission fluid needs to be changed when dirty; typically every 35,000-50,000 miles "
2015 Mazda 5 Sport
Change means drain and fill. Flush gets every bit of oil fluid out and replace with the new batch. If you drive fine after flushing it at 85k miles then just change it every 50k miles afterward (@135k, @185k, etc) should be fine. Of course it also depends on the type of fluid you use (stock type M V one has shorter life than something like valvoline. There are a few threads on this forum discussing the best fluid for Mazda 3/5 auto), if you are towing, and driving style etc.
Thanks @teetee1

I used Valv MV for PS.

Because dealer did the flush, they used Mazda's. For the subsequent drain-fill, are you saying there are better fluids than Mazda's? I got this habit from using dealer Tranny oil as Honda Trannnys are notorious!