Feetup:
For the type of sailing we do in BC waters - for the most part short hops in sight of land -where you are referring to
charts to pinpoint buoys, rocks, entrances to bays and coves we've always liked to fold them into manageable size so you can hold them in the cockpit while conning.
Also, as Surf previously noted, that way they will fit into a large ziploc bag when it rains. (a non issue this past summer!!) This also makes them much easier to store in smaller boats with limited space compared to rolled up
charts.
The downside to folding
charts, especially if heavily used is that after some time the detail on the fold becomes obscured. (Less of a problem nowadays with plotters as backup, but....) Realistically, having to buy a new chart every 5 years or so is not a big deal, and it will keep your chartset more current.
The demise of our old "strip
charts" is unfortunate, they were good for cockpit conning right out of the package. The newer (though very good, complete and detailed) chart books are much less convenient to use, pretty well impossible to fold and also difficult to store. But that's the way our chart service is going. At least they come in a large ziploc bag.