Subpart Q is indeed mandatory for all EU states from july this year. However if local regulations are allready more restrictive in each and every single case they can remain unchanged. In most states Subpart Q will be adopted with some remainders of previous local regulations in force so that indeed duty time regulations vary between pretty much all european states.
In germany we have a very difficult time adopting subpart Q since the final german adaption is not through the legislation process yet so introduction time will be very close to NIL.