What is the purpose of doing a Final Walk-Through when you are a few days away from closing escrow?  (Escrow is the neutral third party that handles the transaction between the buyer and seller.)

A Final Walk-Through is not the same as a home inspection.  It is not a time to begin negotiations with the seller to do repairs, nor is it a contingency.   A final walk-through should be performed at least 3 days prior to closing escrow and it's primary purpose is to make certain that the property is in the condition you agreed to buy it in -- that agreed-upon repairs, if any, were made and nothing has gone wrong with the home since you last looked at it.

You don't need to wait until the last minute to inspect a home for all repairs, especially those that cost a significant amount of money to fix.  For example, if there was a new roof installed or a cracked foundation repaired, you absolutely want to verify several days before you close escrow that all the work that was agreed to be done in writing, was completed to your satisfaction.

With that being said, let's say for example that you closed escrow and then checked on the repairs.....good luck getting the repairs done in a timely manner, let alone at all.  You have far more leverage to get the owner to repair the home before the purchase has closed than afterwards.  After the closing, you own the home.  It is very difficult to get someone to repair your home regardless of the promises made by the seller.
Here are a few items you should check on during a final walk-through:

    Turn on and off every light fixture.
    Run water & look under sinks for leaks.
    Test all appliances.
    Check garage door openers.
    Open and close all doors.
    Flush toilets.
    Inspect ceilings, wall and floors.
    Run garbage disposal and exhaust fans.
    Test heating and air conditioning.
    Open and close windows.
    Make sure all debris is removed from the home.
    Did the movers bang up the walls, rip the rugs or scratch the wooden floors?
    Were the moldings around the doors damaged when they moved an appliance from a room?
    Have all the items that the seller agreed to remove from the home out of the home?
    Did the seller leave "junk" behind in the basement, attic, yard or garage?
    Are all of the items that the seller agreed to leave in the home still there?

Now, what happens if none of the repairs were made?  My advice is to delay the closing.  Remember, as a buyer, you still have all the leverage at this point.  Without the transaction closing, the seller cannot get their money.  

In over 8 years of selling hundreds of homes, 99% of the time the seller will have the work done to your liking.