The seam of a granite counter top is epoxied together. Settlement will crack the granite if the settlement is enough to move the walls and/or floor. Seams are necessary if the "ell' shape is longer on both legs than the slab is wide. So, if you have a 6X9 "ell" and your slap is 5X11...you will need a seam.

Also, most fabricators will generally put a seam at the sink. This is done so that the seam is the least obvious as possible, and so that it strengthens the stone. Having a large hole in the granite can create a weak spot. By seaming it in this location, it adds strength to this area.

The answer to your question, as Ironwood said, is no. A seam is necessary when a) your slab is not as long as your run, b) your run fits on the slab but is too big to carry, or c) the design of your home prohibits a large piece being carried in one piece (basement, small door etc).

We often hear concerns about seams. Clients want to avoid them at all costs. However, a seam is not a problem if you have a fabricator who knows what they are doing and does quality work. We try to position our seams wherever on the countertop will allow for a)the best match in pattern and b)where the eye won't look for it automatically (i.e. not in the exact corner or right at a dramatic vein in the granite).

Here are some pictures of seams to reassure you that, if you go with a quality local fabricator (such as Stoneshop, Granite Grannies, or the team Ironwood uses), then you don't need to worry about the seam: