One of my students brought this to my attention: there is some analysis/advice out there that basically says that each and every RC question is twice as important as a CR question, and thrice as important as an SC question. I had not heard anything like this before, but in case anyone else is thinking of acting on this, keep the following points in mind:
1. The GMAC has refuted this in the past (in response to different variations of the same basic question, such as "is RC more important", "is CR more important", and "is SC more important".
2. An adaptive test really doesn't work like this. The difficulty and "weight" of each question depend on the response pattern obtained during the testing phase, not on the question type.
3. A quick analysis of ESR data doesn't support the view that RC is more important than either SC or CR.
Full analysis of data from 6 ESRs here.