skycake2020 gave the most important point: once you hook them you have until you run out of stamina to reel them in. I haven't seen a big difference between repeatedly spamming the right mouse button and just holding it down. I eat some sausage, fish and queens jam before I fish and can easily bring a fish in from 15-20 meters out. One other thing to note is that you don't have to reel them all the way in. If you get them to a point where you can target them and press 'e' you can just grab them. You can also run backwards and sometimes drag them out of the water and up onto the beach.