Absolutely getting to the bottom 20% when I'm doing it right ("right" == faster trip). That makes the charges faster at each stop. Also I find it more fun to stop every hour for 5-10 minutes than every 2 hours for 30-40 minutes. Of course at some stops with long stretches you have to stop for longer (looking at Kingman, AZ to Flagstaff, AZ until they add a charger at Seligman).