Intersceptic - this has been the new structure since the start of September. You will be required to reach the RAFFT fitness levels in Part B, rather than the (lower) levels formerly required for the PJFT.
Try looking at The Student Room - they have a thread running over there on the new structure. Once you are given a date for OASC you will also receive details of the precise structure and required fitness levels.
AFAIK it has nothing to do with reducing the waiting time from OASC to IOT; it has more to do with trying to avoid wasting the time of overstretched medical staff doing medicals for the large percentage of applicants who are subsequently turned down.