Thanks for your kind assistance; I will start by modifying my hooks on the commercial wobblers and check the impact.
Regarding the XP/Level influence, I guess that it is of an utmost importance: if the size of the fishes you catch would not increase with the Level, one could never afford those expensive equipment.
I would even say that this progression is the very engine of the game.
It's just that, when you are a beginner and you see these amazing posts, you may believe that you just have to place yourself in the same conditions to get the same results.
And many on this forum already explained that it is not the case.
Pushing a bit more on this line, it might be possible to evaluate the average income/hour vs Level built in the game (regardless of all the randomness) : something like 75 silver/hour for Lev 5, 180 for Level 28, 400 for level 33 ... and deduct how many hours you will have to fish to get this nice reel you dream of