What training does

Training raises your fishing skill. Higher fishing skill means longer cast distance, longer reaction windows, and a faster catch animation.

When to train

Train between rare-class runs. Cast on common fish, intentionally avoid pulling, and let the cast distance push out further each time.

Train -> upgrade -> rare-class

The order matters: train first, then upgrade your rod, then chase rare-class fish. Reversed, your rare-class runs will leak fish to the shark.