the firm I work for mainly represents hospitals, individual doctors and other medical practioners. It really all depends on the client. The hospitals we represent do not wish to sue if the balance is under $800.00 but that does not mean they can't if they wished to.
On the other hand, some of our clients (such as dentists, special surgeons) will sue on almost anything even if our firm does not recommend it due to the balance being so small (sometimes as little as $225.00). I always tell them that the costs to litigation does not warrant filling suit but they don't care they do it anyway.