Yes. You earn interest on whatever USDC or BTC balance is held in your Savings Account at 11:59 PM EST daily regardless of whether you traded that USDC or BTC that day. For example, if during the day you trade USDC for BTC you will earn interest for that day for that BTC but not for the USDC you used to buy that BTC.
For U.S. states in which Ledn Trade is available, effective April 4, 2022, U.S. clients will no longer be able to earn interest on any newly deposited or traded funds within their BTC or USDC Savings Accounts. Existing U.S. clients with a balance in their BTC or USDC Legacy Savings Account will need to move their funds to the BTC or USDC Saving Account to be able to trade.