The chain reviews your HBD holdings over a 30 day period and then calculates based on the 3% APR how much you should get. If you do not move your HBD, as in add some or remove some your interest will continue to stack but it won't be paid into your wallet. The moment you perform a transfer it will be paid out and then the next payment batch will then start from 0 again.
So if you don't care about it you can just leave it and collect it when you feel like it by making a transaction. If you have a large amount of HBD could be worth making regular transactions so you get your payout every 30 days
Thank you for explaining that.