That is actually incorrect. It takes in account for mileage, temperature, speed and a bunch of other algorithms shit to come up with the percentage of oil life left. 7500 might be fairly close but it definitely not just based off of mileage. It's all done through the PCM.
I've had my truck tell me to change the oil relatively soon because of long idle periods n such. Dealer says change it at 20 percent or less. You just have to adapt your own policy you feel comfortable with. Mine is more hey I got nothing doing today. I buy new oil and filter every time I change it. And just shelve it. You never know when a long trip is just gonna pop up.