Amazon’s first warehouses in Seattle were tiny(maxing at 60k sq ft as I recall), then 200k in Delaware, then 600k+ in the next few in Nevada, Georgia, Kansas, and Kentucky with the first generation of partial automation(tilt tray sortation systems).

It was easy to sneak off to the bathroom in the smaller facilities.

The bigger facilities had dispersed bathrooms, but depending on the specific job role/location it could be quite a long walk back/forth to use it.

Most of a break period could be spent traveling to/from a break area.

I’m just guessing, but I suspect facility design for the many more recent fulfillment centers(100+ since the early ones) take into account employee traffic/movement/efficiency based on data from existing centers.

A few of my former peers and direct reports are now in quite senior roles in operations for the company.

They are genuinely good people, good managers, and good leaders.