I just get a huge, huge, huge drive, record until they tell me not to! I finish the job! And then I take it out and feed it to the birds while watching them dropping down from the sky!!! Then I get a new one!! And then I go to work again!!! And more birds!!! New trip to the shop for a new drive!! New job!!! Oh the horror!!! Nah, just kidding. I don't do that. I usually use my drives until they formally apply for a retirement. I just buy them really big and then hope I won't run out of space. I never really worried about that. But trying to understand this math, well simply put, I think Bitflipper had the best answer
Phew - it's time for the weekend...