Miles or months (years)? I go 5,000 miles. That way it's simple: when I hit an even 5K miles (5, 10K, 15K, 20K, etc), I get an oil change.....
The "every 3,000 miles" is something that Jiffy Lube successfully implanted in people's minds. If you look at your owner's manual, most will say 5,000-7,500 miles.
I go about 5k miles in the old truck ( might take a year) and about 9k miles ( when the sensor says to) in the Honda....could be 3 months.