When creating a new hashed collection, it will perform a presplit and move chunks to the other nodes. However, the move chunk command can fail for a couple of reasons:

1. Migration already in progress on the donor.
2. Migration clean up is in progress on the destination shard.

As a result, the initial chunks will be unbalanced. This would mean that the balancer would have to move them later on, which is not ideal since moving chunks of a hashed collection is slow.