Max is designed so that you can't inadvertently request overlapping transfers (i.e. Max confirms all transfers are complete before it will allow you to initiate another transfer, so as to avoid the risk of overdrafts). However, with Max, you still retain full and direct access to each of your bank accounts, so you can request additional funds transfers on your own even when your Max optimization is in progress.
To transfer additional funds between your accounts while an optimization or Intelligent Funds Transfer is already in progress, login to your online savings accounts and select the "Transfer Funds" menu item. Select the account from which you wish to pull funds, as well as the destination account, enter the amount that you wish to transfer, and click to confirm.
Funds transfers requested in this manner typically take 1-3 days to complete. If you need funds sooner, you may contact your online banks by telephone and request a same-day wire transfer.