That is very subjective and depends on how well you retain and can recall information. If you have good basic learning skills and like the subject it will stick rather easily. In larger aircraft ingesting to permanent memory the following is a good start. Check list red box items; understand what they do. Flows that comes with repetition. In light aircraft in the beginning knowledge of basic flight and the physics of flight will always help. Don't over study in a single session multiple times usually works. What always helped me was writing the information on a white board first with cheat sheets, then from memory. Then take each system apart and be able to simply schematic it. In my first FE rating I had no access to the planes as they flew 20 hours a day and were never in the hanger. I studied from photos the most terrible way to learn. The day of the ride I was not concerned about the operation of the machine just the walk around. So at 4 am when the plane DC8 61 was in the hanger I went and assisted my knowledge using a grease pencil to arrow the flows of the plumbing and the names of the openings, etc. Grease pencils work great on aluminum. To my dismay the FAA air carrier inspector went first with me to the number two engine slam dunk pointed everything out and he said, "you finish the walk around I am going on board for coffee." All the great art work coding I did for the rest of the plane was wasted. My partner failed; a professional FE no less, God works in strange and wondrous ways. Ultimately he finished and retired a 777 captain.

All the other nomenclature coding went to waste; many years later in the Pacific I could still see the information like it was new. This comes under the aviation rule the innovator will always out perform the regulator. This was a JFK airline that flew mostly military charters and was absorbed by a major. The difference in training can be simply distinguishable by this; engine outs and serious stall serious were done in the plane at/and over Atlantic city at three am! Stall serious buffeting like seriously rough, OMG was that exciting. I did the 727 the same way and always recall in the Boeing manual it says it takes 5,000 feet to recover from a deep stall. At the major it was all simulator time until the IOE. The rules are always the same, limitations, flows and systems knowledge, all else will fall into place for you. Regarding GPS attack this differently, just simply ask yourself, SELF; "where do you want to go and how do you want to get there; the rest is just input and interpretation. Worry is the the worst enemy of aviators. When you know a subject you wont need to worry and you will display confidence because you have the needed knowledge. If in doubt ask those who have gone before and almost all will be happy to show you how smart they are and that will help you. It is also helpful if you do a survey of your examiner likes and foibles; they are amazing creatures of habit, many giving the same ride over the same course and the same turns around a point tower for years. My instrument examiner gave the same ride from TEB to White Plains airport for 5 years with the same holding instructions. So who needs cliff notes when you have history on your side. Never let fear hold you back stay the course it is worthwhile.