There is a lot of subtle and often overlooked execution information that can be learned from Long Form One. The vast majority of this information is absorbed through perfecting the form through practice and through feedback from an instructor. Often this feedback and 'perfecting' is minute and absorbed through repetition and repeated correction. Also, this information is often absorbed over a long period of time, over a large number of practice sessions, and gets almost to the point that the information is absorbed subconsciously. To quote an often used phrase - 'One cannot fool experience'.
Also, perfecting the execution of the other American Kenpo forms can help improve the execution of Long Form One. Therefore, it is not recommended that the practitioner preclude the practice of the other forms for this one. The diverse movements of the other forms can and will help to improve the execution of the seemingly simplistic maneuvers of this form.
Even though Long Form One is a relatively basic form, the skilled eye can easily discern differences between practiced and knowledgeable executions, from those that are more primitive and/or less experienced. Timing, elimination of wasted motion, settling, power, and smooth execution are only some of the factors that comprise a properly executed form.