What -- me worry?
For myself, I don't have a WC plan, nor do I intend to purchase one. I visit client sites very rarely (one visit to one client a year is typical), and all of my clients are in different states or countries. The complexity of insuring coverage makes the risk mitigation not worth the effort and expense.
For those who regularly visit clients that are all in one jurisdiction, the story might work out differently.
YMMV