Try insuring them when you use ff miles! If you have to cancel a trip and redeposit your miles, you will need to pay a fee. Last time I paid it was $150 to Delta but that might be higher now.
Our insurance now covers the redeposit cost, any change fee on your flights and more.
Now if your airline changes the flight on you; you usually have the right to get miles back with NO fee. You might have to call them and ask for the supervisor, but you will avoid a fee.