Discussion started here around auto settings for sharding: https://ossci.zulipchat.com/#narrow/channel/423692-Zarr/topic/Sharding.20performance.20issues/near/553649122

At the moment, the default is twice the number of chunks along each axis i.e., 2 chunks per shard for one axis, 4 for 2 etc.

The proposal would be to add something like zarr.config.max_auto_shard_size that is used when someone passes in shards="auto".

In additional, we could have min sizes as well potentially, see the arguments to _guess_chunks which has both