OG 11 question # 33 IT IS...THAT... construction

[rahulg83]

The answer choice uses IT IS...THAT... form

Although schistosomiasis is not often fatal, it is so debilitating that it has become an economic drain on many developing countries.

In SC strategy guide, 3rd edition, page number 28, it is mentioned that GMAT avoids such kind of construction pattern which uses IT IS...THAT... form. Please shed some light on exactly when to use this kind of expression and when not to?

[StaceyKoprince]

On that page, it also says that this is a preference, not a grammatical rule (in fact, grammatically, the construction is totally correct and you can use it whenever you want - it's just not preferred because it's wordy). IF you have the option to use a simpler construction in a choice that does not have any other grammatical errors, then choose the option that does not use the "It is...that" setup. But always deal with grammar errors first. Concision issues are strictly a preference, not a rule, and are only to be used as tiebreakers after you've dealt with all grammar issues.