Even every third is a lot. Most manufacturers recommend 30,000 miles unless you tow or do a lot of city driving.
And all.
Every third oil change, with following a 10K schedule to add 30K, it is not over kill at all.
to
Every third oil change, with following a 5K schedule to add 15K.
You are changing out 3 qts only, you are not over killing it, but what you are doing is keeping the original mixed in , and I know you'll say contaminating the new fluid! You are extending the fluid till you are ready to change it out fully, which you and most do not do?
To wait to 60K, or do it at your leisure, your choice.
Keeps the transmission clean.
If you have an upgraded kit to your car for towing, or driving stop & go, it all leads to again how you maintain your car.
If you ignore your change, and it goes over the mileage, you may do more harm than good when changing!