You can book a flight way in advance, but there is no guarantee that your schedule will remain the same or even close to the original. Look at this round trip mentioned in an article today in the Wall Street Journal, the outbound flight changed by 12 hours! Imagine the hotels or the rental car companies doing this? Hope that never happens. Notice that changing the rental car resulted in an up-charge of $101.00!
What can we do about this, other than stop flying? Nothing.