Agreed. Remember if it is a true MI, CPR is just keeping the brain and organs alive until an AED is brought. People can look like they are having an MI when something else could be wrong.
Remember to shake & wake, check for breathing and pulse before you start pounding away on their chest!
I also have never had to hug a wall that long. However if it is taking a while my partners and I will take turns helping in the ER if we are allowed. Just to pass the time a bit and is usually appreciated by the staff.