I get very tired at art museums, so once I get the lay of the land, my next visit is usually just one or two pieces, for maybe 10 minutes of absorption. Examples: the Frank Stella wall piece on the staircase at SF MOMA, the painting at the National Gallery East by some Dutch master from the perspective of inside a deep riverbed with two bridges and some city buildings above, the Iranian metalwork vessels with amazing mosaic bead work at the Sackler Gallery. In and out, tightly focused.