What I've seen is when some anglers string up their rods for a day's fishing & put the fly in the rod's hook keeper, they pull the line waaaay too tight. This creates a bent rod tip. They walk around like this, with their rod tips bent. Please don't do this to your rod. It creates unnecessary stress in the rod tip & will - over time - make a weak spot in your fly rod. Even worse, some anglers leave the rod like that in the car or truck as they drive around. It's just not a good idea to do this.
So, when you're stringing up your fly rod & you put the hook of your fly in your hook keeper, reel all the loose line back onto the reel, but only to the point that the fly line isn't dangling & your rod tip is STRAIGHT.
This is what a rod looks like when the line is pulled too tight against the hook keeper:
You wouldn't lick poison ivy.
You wouldn't clap between movements of a symphony.
You wouldn't ask a lady how old she is.
You wouldn't sit on a porcupine.
You shouldn't bend the tip of your fly rod unnecessarily. It doesn't matter if you spent thousands of dollars or just a few bucks for your rod, don't shorten it's life by keeping the line too tight. Someday, probably at the worst time possible, you'll wish you hadn't.