The first thing that comes to mind is: While the time-spent entries I enter are usually exactly what ends up on invoices, on occasion, this is not the case. An entry might get edited (text description of work done, or even amount of time spent), or deleted, prior to generating the invoice and sending it. The concern here is that if clients are notified "too quickly" about time spent, updates would cause confusion, or there might have arisen certain expectations from the client that would end up not being met.