Before I venture beyond beyond home waters I click the "sync" icon and go raid the fridge while the new charts are downloaded and updated in both raster and S-57. When the laptop comes aboard the boat it has all the latest updates. I use the Garmin GPS with outdated Bluecharts at the helm, and when I need more detail I look down below at the laptop, and if the electrons ever stop flowing I do have Maptech chart books (not updated) stowed under the settee cushions.

As Todd pointed out, granite doesn't change position all that often so most of the changes have to do with marked channels in shoaling areas and buoyage, which is all pretty obvious using the 'ole eyeball. The chart changes are necessary and nice to have, but in most cases not much of an impact on safety.