Given 3 months the
MGMAT stuff is definately not too much to cover. However if you only have a month and work full time it probably is too much. It all depends on how much of your free time you can devote to studying. The
MGMAT books don't have any real-GMAT examples. What they do is teach you a topic, say ratios, then give you a 15 question quiz at the end to make sure you understand the concepts. What is fantastic about these books, however, is that they analyze all of the official GMAT questions in OG12 and break them out by category and difficulty level. This is why I mentioned that you'll beed to get the OG 12th edition in addition to the
MGMAT books.
(From my
MGMAT Word Translations book) OG12
ratio questions:
Problem Solving - 20,52,55,63,66,76,96,103,118
Data Sufficiency - 44, 58, 111
Advanced PS - 162, 169, 179, 192
Advanced DS - 155, 163
If you're short on time I'd recommend the following
MGMAT books in their respective orders of awesomeness.
1. Sentence Correction
2. Number Properties
3. Equations, Inequalities, and VICs
4. Word Translations