Probably better nowadays to just calculate distinct grades for each of the different classes of time limits on demand?
Much like is already done with rapidplay grades, but available for people to look at via the website if interested. After all, if you're picking a team/board order for evening league time limits you'd want to know who plays well at those time limits
Might amuse people to know who's doing best in each competition each season too.
As well as data, infrastructure is the other big problem to all of this - the grading website is clearly non trivially under resourced right now