Honestly, I never had an issue with any fishing from any generation-- they all seemed pretty easy to me (including getting the hang of pressing A everytime in... Sapphire? Leaf Green?).
My only frustration was always getting Gyarados instead of a rarer Pokemon, like Dratini or Dragonair, in Diamond-- then again, that's what appearance-rates are for. Not so much a fishinig mechanic as it was a wild-encounter-mechanic.