Put it simple, we can create X-accounts, and then transfer crypto to the X-accounts, then the interests are paid out weekly (every 7 days). If we upgrade to X-accounts plus, we get additional AERs. For example, the X-accounts give 16% AER for USDT. The down side is that it takes 30 days for the funds in the X-account plus to become available. However, during the 30 days period (unlocking), the interests are still paid out weekly as scheduled.