I'm with Ghengis. Yes, the check should be done if possible, and my company requires them on the 744 (a throwback from the Classic?) but somewhere like NWK/JFK/SFO/LAX/BOS(or any USA airfield with inadequate lighting/complex taxy routes/narrow taxyways for that matter) where taxying is about the most perilous part of the trip, it should be optional IMHO. The diagnostics should and will highlight any discrepancy.
Map shift is largely a thing of the past with GPS updating. The FMC will take the best position, and this always seems to be the GPS. TOGA updating on the take off roll may not be the best postion - does that still happen with newer systems with GPS update?. in my experience the aircraft database is not the most accurate info. Nearly always, the GPS pos and Jepp plate agree on IRS align, the aircraft database is often slightly out.