I feel a bit like I’m beating a dead horse here, since we had a similar discussion not all that long ago, but I keep coming back to the idea so I kinda just wanted to hear what perspective you all have :b
… what do you all think about changing the grading system to be drag&drop on a sort of ladder, instead of the current system of single book comparisons?
Something like this, with books in the same row being marked as the same difficulty and the higher ones marked as more difficult:
Should drastically reduce the time needed to grade if the system ever got updated to being able to incorporate infinite comparisons from a single user.
Want to change the grading for a book? Just drag it around instead of having to delete all gradings and do them again.
One could potentially even extract more information, like roughly how much more difficult you perceived a book to be instead of just “harder” 
