Until you learn you've been farming the wrong mob all along. When I was a kid, I was given a "hard problem to solve" by a friend. I tried for years, until a math teacher of mine when I was 18 saw me try to solve it, and just told me "good luck with that, it has been mathematically proved it can't be done".
I'd rather know something is impossible, but when it's possible, try as long as needed to succeed . That's why with hansjoachim's post, once I knew it was possible by just changing my input/output rail spacing, I found my own implementation.