Thanks for the explainations. I think I got a good grasp of how that works now. I didn't realize that it only counts the uphill and not the downhill. That makes a 3500 ft gain over 50 miles not seem so bad knowing that.
Here are a few more questions related to this topic:
1. What grade is considered steep
2. Are there any programs or apps that can give me the elevation gain of a particular route without having a cyclocomputer that either has an altimeter or gps function?