I thought of posting this on the bug tracker as an enhancement request but wanted to make sure it was plausible first.
Currently there's two ways to partition. Either by each individual letter or partitioned.
With first letter, you get a separate partition even if there's only one entry for that letter. With partitioned, you get a fixed amount of entries, but sometimes the first letters get split up.
Would it be very much effort to add a third way that's kind of a mix of the two? e.g. 0-9, A-D, E-H, I-J?. So that it has less partitions then first letter but doesn't split up the entries sharing a first letter.
EDIT: I also noticed this when using first-letter partitioning and I was half-hoping that this might also be a way to partition this by century or decade