Let's let the advice thing slide for a minute.
They sure make playing 36 or more much more doable, just from a physical standpoint. My guess is making that trek on Bandon Trails up to #14 wouldn't be a ton of time if it were the second 18.
A good caddy is also a great asset if it's raining/drizzling, which it certainly does from time to time.
Lastly, they sure help in the fog. I don't care how familiar you are, when you can't see, it's tough!