Are cheap C-clamp trays durable, or do they loosen over time?

This is the most honest point of disagreement in the data. High review volumes and 4.4-star Amazon averages suggest most buyers are satisfied, but a high-trust r/Ergonomics thread reports VIVO clamp screws working loose over time to the point of near-failure. Periodic re-tightening appears to be a real-world maintenance item for budget clamp-on trays.