You can claim accrued interest every 30 or 31 days, I forget which. It's not a lot unless you've banked a decent amount of HBD, but in a scenario like we're seeing now where Hive is higher than HBD it's a perfect time to sit back and collect (IMO) instead of turning it into Hive.
But, I mean, take my advice with a grain of salt. I'm just doing what I think is best given that my stupid bank gives me 0.02% interest on savings and HBD gives me 10% so it's (to my mind) a far better return on money I'd just be leaving to gather dust, and since crypto is so often so volatile, it gives me a chance to play a longer game of waiting for the right time to convert and pad my HP.