Groundloop,
You are indeed correct that the essence of the rostering is to follow 5 earlies/ 2 days off / 5 lates / 4 days off and so on until after 16 weeks you do a month of reserve which is rostered randomly.
Unfortunately the company has produced a 'rostering protocol' (some of which has been published here) which reduces leave, takes back days off and reserves the right to vary the system as it sees fit.
The roster pattern is seen as a positive improvement but the restrictions of the protocol seem unacceptable to most.