There's not much to study. Your tx goes in and waits until inclusion in a block. If your fee is lower than competing tx fees, you wait. If mempool fills up and your fee is too low, you won't be able to enter mempool. If you were already in previously, you aren't likely to actually get dropped since miners keep bigger mempools (> 300 MB).

If you want to pay the lowest fees possible and get in a block in some reasonable time, start at 1 sat/vB and RBF when you feel like you've been waiting for too long.

The key point about the mempool is that it's not a global state -- obvious, if you think about it, because the only consensus is the longest chain, and mempool is by definition not yet on-chain. Every node can manage their mempool independently according to whatever rules they want.