Mutt dont forget I was posting to passengers so I had to keep it uncomplicated while still sticking to the point. I did mention that VR can be burnt enroute. What I said also was that its not PLANNED to be burnt. If its a very good day its not touched.
Yes your right with regard to use of FR for holding at the Alternate, but a declaration of Low Fuel State must be made to ATC (I know its in the Jepps somewhere). But using the 737 & 747 QRH as guides, a low-fuel emergency condition exists when total endurance reaches 15 minutes or less. Cutting into the 30 minutes for any reason amounts to an Incident in many Company policies and Civil regulations. It does in ours too.
Some States allow for a reduction of FR to 20 minutes during Depressurised Ops. That means however you only have a 5 minute buffer from the requirement of having to declare an emergency low fuel state to ATC.