Many "accumulative" awards of DFCs for example were often awarded at the end of a Bomber Command tour during WW2. However, it was considered that the sentiment of losing a colleague could lead to an accumulative award for being a nice chap and therefore they were made posthumous to avoid this.
I'm slightly confused by what you are saying
Wensleydale. I get that a lot of DFCs (and DFMs) during WW2 were "end of tour" awards. Are you saying that people were being written up for these awards after they were killed? If so, that certainly goes against what I understood to be the regulations at the time. Correct me if I have misunderstood your post