The first one always takes way longer than the code itself deserves. Most of the work is figuring out the unwritten rules, not writing the patch.
Can confirm that it also happens in other complex systems! Still a lot of good time and the novelty factor helps with pushing through
Sand that after so many years these rules are still not written down.
This is a big problem in open source that seems taboo to discuss.
In my opinion, unwritten rules are for gatekeeping. And if a new person follows all the unwritten rules, magically there's no one willing to review.
I think this is how large BFDL-style open source projects slowly become less and less relevant over the next few decades.