Originally Posted by
username
A good rate is when the miles you buy for your trip cost less than buying a ticket. Since the miles needed for trips after 15 November on United is no longer predictable, it has made the math a lot harder.
As other have said, it only makes sense if you need a few miles to top-up and get you a ticket that you will book immediately.
Not necessarily. Award tickets don't earn miles or credit for status. They can be treated differently for upgrades, etc.