Just using the good qualtiy Penzoil Tranny Oil (I think it's 75-90 wt) has kept our tranny in great shape for 320,000 miles.
1989 Corolla SR5 5 speed.
I have only changed it 2x. (not sure if any lube was done by a shop for my wife, if so maybe 1 more time) . It last a very long time..
But it is just regular street driving... but in city driving none the less with heavy stop and go traffic with short freeway runs..
also in San Diego the summer can get hot, but seldom gets cold, which is never below 45 degrees. So, if you are in a climate with all the etreme weather, it maybe better to change it more often... or if you race it around.. or on mountain roads..
the drain plugs tend to get rounded corner because the plug head is too damned thin.. so make sure you use the proper socket for a tight fit and make sure it is squarely on the bolt... it usually needs a breaker bar...
