I agree that network can be very funny most times, and it's a bit difficult to tell when some wallet has fully synced or not, until you've made an attempt to make a transaction. Do you have an idea of the average time it takes a wallet to fully sync?, because I think there might be some cases where a transaction would fail to broadcast despite using the actual fee at that point.
I don't think synchronization actually has a particular time it takes
for. For your wallet to sync with the blockchain
, basically it differs based on many factors ranging from the particular wallet software you use to how many UTXOs you have on your wallet. This simply means the more the input and output transactions from your wallet the longer time required for synchronisation.
Quick question, Who has experienced a eviction from the mempool as a result of spending of a single UTXO twice
Where the first transaction hasn't been confirmed hence the other had to be removed?
Same situation could cause an eviction from the mempool but the OP did specify lower fee
It is actually possible but the chances are quite rare basically miners are very smart when it comes to selecting transactions to mine which simply means if you double spend there's a high chance they will confirm the one with bigger fees first and discard the other one.