Both my daughters wear gform pro x elbow and one also wears their knee guards . It's only light impact protection. Discreet enough to fit under a long sleeve top , reasonably cool , nice and flexible. They're not really built for abrasion resistance - more initial impact dispersion.
My daughters don't fall often, but I've watched my youngest drop 2 metres with her knee cap landing on a rock , she got up and said " glad I missed that rock"
Unfortunately the cut has changed in recent years with longer tubing closer to the body, still a good product but not as cool