Art looking marathon

Many people race through art musuems casting brief glances at the art. Mona Lisa, check. Starry Night, check. Campbell's Soup Can, check. Seems like people spend more time reading the informational plaques than they do looking at the art. Art critic Jerry Saltz seems to be a marathon art viewer claiming to have once spent 11 hours gazing at Velazquez's "Las Meninas," among other feats. I can't compete with Saltz, but I've learned a lot by sitting quietly looking at art for a long time.