Mystic;
Most, but not all. My volvo calls for 5K "severe", and my chevy has the oil life system, and says to change at 3K only if you drive in very dusty conditions.
The point is, read the manual and do what it says. If you drive "mostly" under the conditions they say for severe service, then follow that interval. If only some of the time, then shorten your interval as much as you feel you need to (that's why 5K might be a good compromise if you do a mix of driving).
Just don't blindly accept the Jiffy Lube / oil maker mantra that "everybody drives under severe conditions". If severe conditions were normal they would call them normal. That Consumer Reports study was seriously flawed (like few cold starts), but the one thing that we might be able to take from it is that "stop & go" driving and idling (once the car is warmed up) aren't nearly as bad as they want you to think.
I think you should follow the manual. If everyone's cars start wearing out prematurely then there will be change. The way things are now, many people are changing their oil early (at 3K), and since cars are lasting a good long time, the car makers can say, "see, those 7500 mile intervals are working great! Lets go up to 15K!" And then the quick lubers will say "everyone drives under severe conditions, you MUST bring your car in at 7500". But, hey, at least they'll still flush your ATF every 15K miles for you too if you want.
Getting back to your original question, though, don't sweat the choice of oil.
Matt