Seconded/thirded.
Using L down a large hill means you can cruise control the whole way down and not have to worry about gaining speed (unless it's such a steep hill that not even L can hold you back)
Seconded/thirded.One convenient use of L is that it usually enables you to use Cruise Control and leave your foot off the brake while driving downhill without speeding up, when the car’s momentum will otherwise cause the speed to increase if you try to leave it in CC while driving in D. (Hmm... I wonder if using Adaptive Cruise Control would enable Gen 2 drivers to remain in D while driving downhill behind the driver in front going the speed limit?)