Failures and mistakes do occur so prepare for them.  What would you do if a hardware failure, human mistake, or a hacker event destroyed your entire production web site?  Regular back up cycles are a fact of life and you have to build them into your infrastructure.  The larger your site, the more that this effort will have to be staged or scheduled across the day or the week.  In any case, plan for it and be religious about it.

Today, with the availability of low cost cloud services, every web site can be backed up and prepared for the worst.  Good design of these systems take expert help but integrate this into your plans early so you can keep the cost of maintenance and recovery to a minimum.