Whether that provisional patent application can ever be useful moving forward is unknown and unknowable at the time it is filed, which allows for those who knowingly or unknowingly peddle bad services or bad advice to largely hide behind the unknown. In fact, you won’t know whether the provisional patent application was worthwhile in terms of disclosure until you later need to rely on the disclosure to establish your priority filing date. If your disclosure was not complete you have nothing useful, and potentially may have compromised all right to obtain a patent. You may not realize that the provisional patent application you filed was defective until after you file the non-provisional patent application and you are now in prosecution working with the patent examiner who won’t give you the priority benefit of the earlier filed provisional because it discloses little or nothing. Filing a defective provisional patent application can be catastrophic.