I run a quick lube and even I think 10k between oil changes is crazy. We have customers coming in with fresh expired warrantys and sludge dripping out of their motors (yes literally sludge ) because the dealership told them 10k on conventional oil is fine and 15 for synthetic is normal. I run 3-5k AT THE MOST on Mobil 1 with a k&n oil filter on my 01 bullitt. 75k miles and under the valve covers looks like the days she was born. I know this is not my section but I wanted to give my .02. Hopefully ill start my own 5.0 thread soon

 

I don't know of a single dealership that would tell a customer that 10k intervals on conventional oil is "fine." The quick lane oil change in most dealerships still subscribe to the 3k interval.
All of the longer change interval (7.5k, 10k, 15k, etc) suggestions from the OEM's are all with cars that have at the very least a synthetic blend. Most use a full synthetic. Recently, the 10k interval on Fords came about due to additional oil in the sump like the 5.0 with an 8-qt capacity. Having the additional oil, and using Motorcraft oil (which is a syn-blend), has proven to keep it's protection up to 10k miles when driven easy. Most owners manuals will refer people to the severe usage change intervals anyway, which on the newer cars is 5k IIRC.
On the cars I own, I change at 5k intervals using Motorcraft oil & Filter. On my wife's lease cars, I change at whatever interval the manual suggests. In the case of her new car (2011 Edge), the interval is 10k. So that is what it will get with changes done at the dealership.

 

I switched back to doing my own oil changes when I bought my Mustang so not sure what a quick lube would cost. But with 8.5 Qts of Motocraft synthetic plus filter the cost was ~$70. If its a DD getting 15k miles a year, you would have 3 changes at 5k miles between change versus 1.5 changes at 10k between changes. That is a cost difference of ~$100/year for more frequent oil changes, peace of mind, and most likely a cleaner engine.

I wont be changing my oil every 3k miles, but I trust the input of a quick lube owner that most likely on one month sees more oil out of more cars with different mileage than most of us will ever see.

EDIT: Forgot to add that most of us probably spend more than $100 in mods per year anyway