For this particular approach : https://nftschool.dev/guides/batch-minting/#piggyback-minting-for-erc-721-with-chainlink-gas-price-feed
We are storing Unminted NFTs in an array everytime if the gas is high but we need to take in consideration of the fact that now we are writing to an additional array in the contract which uses the global memory (Storage) and eventually writing to this and reading while minting costs additional cost for each mint. So this approach in my opinion really doesn't help with respect to batch minting.
For this particular approach : https://nftschool.dev/guides/batch-minting/#piggyback-minting-for-erc-721-with-chainlink-gas-price-feed
We are storing Unminted NFTs in an array everytime if the gas is high but we need to take in consideration of the fact that now we are writing to an additional array in the contract which uses the global memory (Storage) and eventually writing to this and reading while minting costs additional cost for each mint. So this approach in my opinion really doesn't help with respect to batch minting.