Most reviews are written and circulated under conditions which ensure that they have a very short active life There are deadlines there are restrictions normally quite severe on their length and when published they claim houseroom only for as long as the newspaper they are printed in  a day or a week at most a month Moreover the literary status of reviews tends to be settled by their ephemerality It is usually supposed not only by the public but quite often by the writers themselves that reviewing is work that nobody would do if there werent some reason  shortage of cash would he cited most often though another good reason is that you cant work all day on a novel or a serious book of any sort  which prevents them from occupying their time with something more valuable