It is ... that...

[Mymisc]

MGMAT SC p210 (pattern 7) says this structure is not concise? How to know when to use this rule or when not?

[tim]

I’m going to go with "pretty much never". First, you’ll find about 1% of sentences that are ultimately decided on the basis of concision. Of those, probably far less than 1% will use this particular construction. The bottom line is it is NEVER worth your time to memorize specific constructions as "wordy" versus "concise". Instead, look at the wording on a case by case basis in those rare cases where you actually have to make a decision based on concision..