Looking at the "about" page for the project, it explains that they're using a special turntable with 4 styli that can record simultaneously. So it doesn't really increase the workload by 4 times to archive in this more thorough way.
That's extremely cool. With decent headphones (ATH-M50x), there is a noticeable difference between the styli, so probably worth the extra work for archival.
The next step up would presumably be a 3D-scanning method like IRENE: http://irene.lbl.gov/