Because it's supposed to. A little bit of oil will slip through the rings and be burnt on all engines...about a quart every thousand miles. That you are using a quart every thousand says to me your engine is nice and tight - gas isn't getting past the rings and diluting the oil.
Honda recommends @ 45k miles and then every 30k miles after that.
A 2004 Honda Accord should have a complete tune up every 100,000 miles. The oil needs changed in the car every 3,000 miles.
Every 60,000 miles...
Honda recommends every 100,000 miles.
Every 70,000 miles.
I recommend every 75,000 miles.
Change the oil/filter every 5,000 miles.
Must be changed every 105,000 miles.
Every 5,000 miles is a good choice when I do not know what year you are referring to.
The timing belt should be changed every 90,000 miles on a 93 Accord.
Honda recommends changing it at 100,000 miles. I personally recommend you change it every 75,000 miles. The 2003 Honda Accord had problems with the transmission so I would recommend this as a preventative measure.
For Honda Accord, you change the timiing belt every 110,000 miles ( V6 ). The 4 cylinder has a chain that requires no maintenance.