I can't comment on how senior officers gain their knighthoods. But for the 'lesser' awards of MBE, OBE and CBE, it is a good rule of thumb that the award says as much about the writer of the nomination as it does about the recipient. There are plenty of deserving individuals out there whose chain of command has failed to write them up for awards, either through poor admin or by applying an unnecessarily harsh level of initial screening. And there are plenty of senior officers out there who couldn't write a decent report or citation if they tried (as anyone who has sat on a promotion board can all too easily attest). But there are some officers whose subordinates always seem to do well come honours time.
As long as different senior officers take differing perspectives on the honours season (from "a pain in the a*se" to "a chance to reward my most deserving individuals" to "a chance to show how great I am by getting awards for as many subordinates as possible, deserving or otherwise") then there will be apparent oversights and inconsistencies. Unavoidable really!