This is why I strongly adhere to WET¹, you discover so much about the domain the first time you write something. By the time you have it 'working' you realize you should've written vastly different code to solve or cut-off edge cases.

That's why these days I just start writing code, get it to 'it works!' level. To then throw it all away and start again. Takes a little more effort, but the payoff is far less problematic code and tech debt.

¹: Write Everything Twice

Don't do WET with your entire system, though, or you're likely to end up with the Second System Effect.