In one of my past jobs I averaged 1500 mile per week, sometimes more. It was an every other Friday chore to get the oil changed (every 3000). When I turned in my last company truck it had 96,000 on it and I hadn't driven it a year yet (just under). It was routine to get up at 3:30, drive to Hilton Head Island (about 7.5 hours from central FL) do a 30 - 45 minute service call and drive back in the same day.
Yes it royally sucked. No I dont miss that job. What REALLY sucked was that I was salaried and never saw a penny for the hours and hours of overtime I put in behind the wheel.