As a result of the many recent devaluations, many have kept emphasizing the phrase "earn and burn". I'm fairly new to the hobby, so each of my airline and hotel balances are below 100k. My United balance is the highest with 99,000 miles. I'm curious to hear everyone's strategy, do you truly "earn and burn" to keep each program account close to zero? Or, do you maintain a high enough balance in several programs in order to cover a last minute or emergency trip?