I can answer that, YES. When flying with plenty / full tanks!
Er no - not if you operate IAW the RFM.
Is there ANY airborne situation at all, where you'd switch off fwd AND aft transfer pump?
Yes - if you have exhausted the fuel in the MAIN tanks.
That would of course leave you with the contents of the SUPPLY tanks remaining.
Depending on your operation IFR, VFR or Ops Manual or NAA reserve requirements that may never or rarely happen if remaining within those constraints.
What do you think drove the design with respect to the SUPPLY tank size?
Interestingly should you fit the "FUEL FLOW" option kit - Time to END is predicated only on the contents of the MAIN tank.