How do fixed term savings accounts work?

Just a student trying to make sense of money.

Take for example the Nationwide Flex Instant Saver, which is what spurred this question. It has a 12 month term at 2.30% interest. I understand that means that after the 12 month term, they will move the money to a lower interest account.

Are you then allowed to simply reapply for the Flex Instant Saver for another 12 month term, or is there some sort of cooldown period, or is it a one and done type of thing? What function does the 12 month term actually serve for Nationwide in this transaction, as it's an instant access account rather than a locked one?

TIA, hope this isn't too basic for this sub.