Common sense used to prevail, on a 4jet taxiing in, if the ac weight wasn't too great shut 1 or 2 eng down after the recommended cooling time.
Now we have to check NOTAM/Port pages and brief it, forgot to brief it? should I still do it. On a big twin you will get a fuel saving only, if the thrust is at idle, stop and increase thrust to break away and your savings are out of the window. New JFO who doesn't understand spool-up times and constantly increasing decreasing thrust lever position, even more fuel used. No doubt there will be a Learner's World program to complete, in your own time.
However, taxiing out in PEK with an unknown delay before T/O that's another matter