Hey mate, excellent post. I agree with everything you said and info like this is great for people who aren't sure what to expect going into exams.
I found the trick with Systems was doing heaps of practise exams and use these as a study guide. There is simply too much content to remember. It differs from other exams like Flight Planning, where you start off doing heading and ground speed calculations, then normal basic flight plans, then backwards plans, then abnormals - each thing builds on the last. Systems is just pages and pages of info, there is about 300 pages of info in the Higgins textbook (not including revision and practise exams) and in theory you could be asked a question on
any sentence in those 300 pages. However, don't wrote learn the answers, some questions appear different on the exam. I would estimate that 90% of the questions in my exam I had seen (either the exact same or a variation of) in either the Higgins or Avery practise exams (I would recommend Higgins though). You last week before the exam should just be going over practise exams, and doing the same one multiple times. If you keep getting a question wrong, go back and study it some more.
Also I'm not sure what order you did the exams, but I would recommend doing Flight Planning and Nav after each other, they are probably the two most similar exams. It shouldn't matter which way around. I did Nav after Planning and I found it like an easier version of planning with some theory thrown in.
It took me ages to do Flight Planning, so I would recommend doing that one first. If it takes you over 6 months, like it did for me, thats chewing into your 2 year window by a fair bit. Maybe do an easier subject first if you want do 'get back into the swing of things' before tackling the beast that is Planning, but just be aware you might have to resit that exam. If you were going to do a course, Flight Planning is definitely the one to do it for.
Here are my ranks from hardest to easiest, plus some tips and the time it took me to self-study:
- Flight Planning - You need to strike the right balance of being accurate and fast. Figure out what the question is asking for, don't bother doing a whole flight plan if you don't need to. [6 months +]
- Systems - As mentioned above, heaps of content. Do lots of practise exams. [2 months]
- Navigation - As mentioned above, I did this after Flight Planning so it just felt like an easier version of Planning. [1 month after doing Planning, allow 2 months if you haven't done Planning]
- Performance - As OP mentioned, just be really accurate. [2 weeks]
- Human factors - Find a good textbook as many are lacking on TEM. I actually failed this one with 67% because I thought it would be easy and I only put in about 5 hours of study. [1 week]
- Law - The only tricky thing is the 80% pass mark. Just get good at finding things and don't try and remember stuff by heart. [1-2 weeks]
- Meteorology - I agree with OP, definitely the easiest exam. [1-2 weeks]
Note: The times taken aren't my recommendation or anything, they are just so you can compare how long it takes to study each exam. I was working full time as a pilot, so things like overnights and checks definitely slowed my progress.