There's three ways to look at this. Any way, you gotta get the dirt out. The problem with these trannys is the filter is not that great of a filter. That's why people get away with just exchanging fluid. It takes a long time for them to clog up. But if and when they do, it's game over.

1) Service with filter change / new fluid. Can't go wrong if you do it often enough. More expensive.

2) Exchange Fluid only. Filter less frequently. Same-o, same-o. A little less expensive.

3) Install a better secondary filter and safely do fluid exchanges and primary filter changes less frequently. Keeps the oil cleaner all the time. far less expensive overall, extends tranny life.

I use option 3 in case you were wondering, and if you don't believe me, I've got two 727s that were manufactured in 1968 and 1970, never been rebuilt, still running perfectly. One has a TF2 shift kit and gets beat on like mad all the time to this day. Both have over 100k miles on them.

You just gotta keep the fluid clean. Changing it frequently enough will do the trick. How frequently is frequently enough? Don't know.
Some people find out how frequently is NOT enough the hard way.

 

Well said. And "frequent enough" varys with usage, location, driving styles and vehicle weight!
Thus the principle of overkill... which sometimes does have merit.

Also worth mentioning, IMO, is a stock tranny needs more careful attention, not less, than say my DTT.
It's easy to be super careful with an aftermarket tranny. You spend a lot of money and want to protect your investment.

But stock trannys have more slippage and tend to run hotter, with less quality parts. The arguement can be made that synthetic fluid, for example, is more important to a stock unit than to an after market tranny. I would also recommend more frequent fluid/filter changes on stock trannys, not less.

As mentioned above... several ways to 'skin this cat'. Just get-er-done.

RJ