And also consider whether the person carrying the boards IS wearing a wrist strap while moving from place to place. Do they charge the boards to high voltage, then put the strap on, making their body potential drop, then touch the boards to remove them from the rack?
Personally, I prefer foot straps, the kind that is a thin conductive plastic strip that wraps under the foot and shoe heel and has folding metal ends you bend over the edge of the shoe. The kind that are like a sling with an elastic/velcro strap that fixes over the foot are unreliable if socks are worn. A wrist strap would still be used at a workstation.
Brian.