It's unfair and selfish to regret a decision when times are lean, but to reel in the profits in good times.
When you're sure that you have hooked the fish, reel in at once.
It is used to reel in and reel out the small cone (shown below) that trails behind the airplane to provide an accurate static pressure reading during flight testing.
But I'll never go into the wilderness, skewer a worm on a hook, reel in a fish.
Daddy helps me slowly reel in the fish.