Woodworking

While looking into workbenches, I came across a suggestion that scaffolding screw jacks could be used to make a large vise, but also comments saying that since they’re designed for use on muddy construction sites, the threads have excessive clearance or slop. Is that a problem in practice? I can’t figure out why it would be, since I would think backlash just means you need an extra fraction of a turn when switching from tightening the vise to loosening it. What am I missing?