The authors suggest...
The "genre-specific" problem is an issue individual programs have to figure out in the calibration process. When I taught at Portland State University this was a big issue. We were taught, however, to put considerable weight or attention on the reflection letter/essay. In fact, it started off a letter and soon became an essay. The idea became that a portfolio should stand on its own: that is, it should largely set out its own requirements in the reflection piece and the various essays, etc. should meet *those* expectations first.