So, I'm about half way through my first round of test writing. I'd say that I'm probably getting somewhere around 80% test coverage. I'm not explicitly testing everything, yet. I also haven't even attempted to get into any of the more complex situations. What I have so far is going to be a fairly basic, yet thorough testing platform. Being only about half way through the product, I obviously haven't gotten to all of the features I would like to have automated. Yet, this is the point where I can see where I'm going.
I think that at some point in the future I'll probably go back for at least one more round of test writing for this particular project. Extensive test coverage (which is what too many rounds of test writing would be) is usually for large teams that have investors and customers. The tests are most helpful when developers have to fix customer submitted bugs often. Tests are actually kinda useless when major changes are made to a product (although, it depends on the changes). But, I do not have any of these things.
I see my testing as an advantage in two ways. One, it improves the marketability of my products. If I'm trying to sell this to someone, my automated tests can be used both as proof of my professionalism and in certain cases, an entry point into the technical details of what I am accomplishing (although, I will have to consider how open I will be with my intellectual property). The second advantage is that it gives me hope that at some point potential employees will be impressed with what I have accomplished. If someone if going to spend any amount of their life working for me, on my code, they are going to need to be impressed with what I have done. I personally would not work for a company that I thought was either unprofessional or not going to be successful.