The only people who can answer your question are within your own company.
In our case, the 15 minutes of fuel is based upon holding upon arrival, you can then make the approach followed by a VFR 2nd approach landing with ZERO fuel. We didnt agree with the VFR approach so we added additional fuel to make it a full 2nd approach, but yet again landing with ZERO fuel.
Now before i scare anyone, thats the way the calculation is done. In our case because the destination is beyond the ETOPS area, the fuel remaining is always greater than required.
FAA Regs...
Rgds
Mutt