I wasn't suggesting that cruise settings vary.
Mine never vary either (10.5GPH, LOP) unless I am above about 10,000ft and then I am happy with what I get with the throttle on full-bore
What I was getting at is that one has to do
something to separate the fuel usage during climb/descent, so one can get a decent grip on one's
enroute/cruise fuel flow.
On most flights, one can estimate the climb usage fairly easily (straight out of the POH; all levers are fully fwd anyway), and the descent one similarly. It is the cruise one which needs to be determined extra carefully in order to do accurate flight planning.