In a search, you always find it in the last place you look.
Patent searching can occur during research and development, when a potential solution to a known problem begins to gel, during engineering, and/or when a solution is base-lined. Searching can occur before or after an invention disclosure is drafted — the subject of the next chapter. Issued patents and published patent applications are usually searched for three primary reasons.
The primary reason is to evaluate the odds that the Patent Office will consider your innovation patentable. Without going to law school or even having been through the patenting process before, you already know (and probably knew by about the 6th grade) that “patent” means invention and invention means new. What is old is collectively called the “prior art” by those in the patent community. A search, then, can be undertaken to evaluate if your invention is really new or has already been covered in the prior art.