SmartPOP2Exchangedoes also checks one account after the other (POP3/IMAP). But after the download messages from one account are processed parallel (including sending to your SMTP/ExchangeServer).You can set different intervals for checking on each account and set the maximum number of messages to be downloaded from on account. that way you can prefer certain accounts by setting a smaller interval and setting the maximum number of messages to e.g. 10 will affect that SmartPOP2Exchange does not neglect any account further down in the account list.
The interval on the "Settings" and on the "Schedule" tab is the same. If you change one that other one will change too.
So this are just two places where you can modify the same value.