Once, in JFK, B767, after being given start and taxi, we then discovered we were No. 50 in the takeoff. queue. With some landings on the same Rwy we calculated we had at least 80mins taxi to do. We had to shut down an engine otherwise we would have departed with less than minimum fuel. It was the first and last time JFK caught me out, thus. Fuel saving, yes, but out of dire need rather than SOP.
I wonder if such an inefficient ATC procedure/system still exists there? If it does it is a real gas-guzzler. And if it does, Why? Can not some sequencing be done with start clearances, or is to vacate the gate for inbounds?