RVSM course with CAE, FS and others say check of altimeters before entering RVSM airspace and then once every hour, which make sense for me!
Capt claret- perhaps you do not check your altimeters in cruise because the ops manual say so, then the comp monitor advise you only when the limit is passed, if you check it yourself you might be able to see the trend and react before you have to leave RVSM...