Most banks use "business days" to calculate transfer time (Monday-Friday, 9 AM - 5 PM, excluding holidays).
If you initiate a transfer late in the day, it starts the next business day. The estimated completion date accounts for this.
Processing times by payment method
Available payment methods and their processing times are available in the relevant article:
Sell to a cash balance
Selling crypto to your cash balance is instant, making funds available for purchases or withdrawals.
Sell directly or withdraw to a bank account
Processing time will be displayed on the confirmation screen prior to initiating the withdrawal. If your balance is insufficient, review your Available Balance.
For instructions on how to sell and withdraw from your account, see Sell crypto and cash out your balance.