Hatches, bulkheads, deck strip patterns. strength. practicality of forms, use of fiberglass cloth. You can certainly construct a stripper in any of the methods you mention, but why? When you strip a hull upside down you get to see the symmetry of the shape at once and spot any non-fair areas or problems. Working on the undersides of hatch openings is a must for most builders as well as any possible deck line fittings. Every builder knows that the deck and hull never match perfectly and the shear is a great place to hide it or force the pieces together. Imagine if that was on the center of the deck and down the keel line of the hull? All the geometry of the design can be compromised. If you have to twist the shears into position a bit, the below-the-waterline design is not altered. Plus, you get to see a view of the hull take shape during the building process with is a nice reward for the efforts.