Airbus optimum cruise levels -
When the FMGC offers an optimum cruise level on the PERF page, is it advisable to to accept it? On short sectors, especially light, there can be a big difference between OPT levels, Max levels and computer flight plan levels (based of fuel efficiency). I know traditional thinking is for 'go as high as you can then descend' but I understand OPT CRZ is to give sufficient time for the engine to operate at a stable power setting for engine life and maintenance considerations, at least this is what I have picked up over the years. Notwithstanding the above, when there is a big difference between OPT and higher cruise levels, is the extra fuel used by staying low factored into the computation? I.E. would a wise and company minded crew tend to follow the OPT CRZ value?