Doc and barkford
MB has been really cutting down on the times for A services especially, and now B services also. An "A" for a 210 chassis is now down to around .9 hours.
Doing an oil change in the 5 to 7000 mile range (the engine holds 8 1/2 quarts) seems reasonable, but don't forget the other work which should be done, like inspecting/rotating tires, looking at the brakes, flushing the brake fluid (every 2 years) and coolant (every 3 years). If you want to develop your own maintenance schedule, that's fine as long as you are comfortable with the schedule you arrive at and it's complete.