For some people like u, the basic rules are sufficient to feel self confident and to master the beast.
first, i don't consider myself too special and i truely believe that anything i did in gmat anyone can do.
and i also agree completely that gmat is 50% self confidence (i'd say even more).
i'm not suggesting that doing difficult non related questions is a wrong way to succeed in gmat, i just question the approach.
if it is, as you suggested, a way to boost delf confidence - i think that there are possibly other ways to do that. abs value equations are not, in my view, more difficult than gmat, they are just different. mastering them doesn't necessarily give you, mathematically speaking, much more skills to cope with gmat questions involving abs value.
our minds, unfortunately, are somewhat limited. so when studying so hard to gmat, mastering so many techniques in a short time - we usually get overloaded we information. this is why i try to avoid using techniques that are not necessary. it is true that everybody can learn to solve equations with abs value. they can learn many other techniques and quant skills, but we can't learn and master all of it in 2-3 months time. we must choose. and we must concentrate on what gives us the highest ROI - skills that by mastering them we gain the most gmat points. i think that equations with abs value are not high in their ROI.
and now for the self confidence.
i think that the best way (i used this method, and taught it and used variations on it in my classes) to boost your self confidence in gmat is to do this:
- define a large but manageable set of gmat questions, that span approximately the range of skills required to succeed. the OG guide is good for that.
- solve those question (always in a timed manner). and review your answers
- solve again those questions, and see your progress....
- solve again.... and see your progress....
repeat until you can solve, in time, without miskates all the questions in the predefined set.
when i say "solve again" i don't mean just marking the answer (which you eventually remember by heart). i mean really solve it... explaining every answer. if it is a data sufficiency - either prove it or provide a counter example. if it is a PS write the solution all the way.... and do it in time. never guess.... always provide a convincing explanation is if you are about to teach it. and always in time. if it is a verbal part question also provide explanations: for RC - go to the passage and show the exact line you rely on. for CR provide an explanation. same as SC.
when you succeed in this you will have a true experience of solving a complete gmat test, in time, answering all (or most of) the questions right. you'll know the feeling of answering a question right and knowing it is the correct answer. you will cherish this feeling and can take it into the real exam.... and you do it by using only those skills that are really required for gmat - not by mastering "extra skills" that might overload your mind.
i must tell you now my own experience....
i didn't have much time to study for the gmat. luckily, i didn't have to study at all to the quant. so i practiced verbal questions. all in all, i solved in a week of study more than 500 questions and doing 5 full CATs. my quant scores were constantly 51 (no surprise here), and my verbal scores went slowly up from 33 to about 40 (sorry... i don't remember exactly). i finished my preparation program at noon, a day before the test. my last gmatprep from the morning was 720-740 (don't remember exactly), which was the highest i got during the prep week.
i went for a relaxing walk in the park, read and answered some work emails i ignored most of the week....
in the evening i became curious if gmatprep can really give you 800... i had some free time i decided to take the same test i took in the morning again. i skipped the AWA part. solved the verbal, happy that i know most of the questions and don't have to read carefully, and knowing some of the answers from the morning sessions....i went on to the math... no problems here (finished it in 40 minutes). i saw my score ...... well it was a 780 (dissapointment.... i wanted to see 800).
looking backward, this last score was an exact predictor of what really happened to me in the test....
so.... my method of boosting confidence ..... do it again and again until you succeed....
thinking of it - it is exactly like a professional pianist (or any classical musician)... in order to play well a certain piece, you practice it over and over again until you know to play it. so is the gmat - to succeed in it you should solve questions again and again (not necessarily different questions...) until you get it right.
well... that's my long two pence.
hope it'll help...