There are various wallets where users mostly sends Bitcoin for example: Any Bitcoin wallet and exchange wallet.
Many people believes 0 confirmation transaction are reversible.
- Bitcoin Wallet (while receiving/sending): Wait for at least 2 confirmation.
- Exchange wallets (deposit and withdraw): 3 confirmation
- Sending more than 10K in USD: wait for at least 10 confirmation
this is incomplete and vague.
- there are many types of bitcoin wallets and each require different number of confirmations (for security reasons). for instance the number for a full verifying wallet is 3. for an SPV wallet that number is 6. and all of that is whenever network is fine and there isn't any fork or anything similar going on. otherwise the number goes up to 30+ read more here:
https://bitcoin.org/en/you-need-to-know#instant and
https://en.bitcoin.it/wiki/Confirmation- there is no such thing as "exchange wallets" even if they call it "wallet" it still is an account and since they have full control, it is their decision how many confirmation they require to credit your account.
- again this mainly depends on the type of wallet.