Ok, so I’m not that bothered about my camera’s clock, but when shooting with multiple bodies and one happens to be 55 minutes slow, it’s a jarring experience to review the full set of images in time order. {Aperture} 3 does have a neat time adjustment tool in Metadata -> Adjust Date and Time
that does, as many websites say, allow multiple images to have their time changed.
What I hadn’t realised until I needed to do it is that whilst you set an explicit time on your pick of the selection group, the adjustment is applied to each image, not the exact timestamp you’ve just entered. Phew: job done.