looking at autostore I was curious how many skus can be done efficiently and how deep you can go relative to the number of fast moving lines? With a million SKUs it might be fun to see what initial mapping can be done. Also, how can hazardous stacks be integrated to they can deliver to the same work station as regular items?

as for maintenance I would think a few strategic extra rows could serve that purpose without losing too much efficiency.

most the picking I am used to has both voice and light based picking with high velocity parts duplicated to the front.