I had private class with my friend for explain Solidity for NFT. I explained basic idea of Solidity and ERC-721. We looked source code of Goblin, Begin as Nothing and BAYC Solidity codes.
We found that BAYC that was release about 1 years ago and Goblin and Begin as Nothing is recent released. It is really different. BAYC used many fixed value in code but other one is not. and recent ones are used ERC721A.
reading code is really good hobby for me. and good practice.