Let's be honest , release to check in on reserve will work sometimes and probably not very often for this on 4 day block, the commuters, the days of the trip have to match the days of reserve left. With only about 10% being 4 day trips yet about 50% being 4 day blocks of reserve it's pretty unlikely a person starting a 4 day block of reserve will get assigned a 4 day trip. Therefore that person will have to commute in just like before.
3 day to 3 day is more of a possibility, so that's good. But all in all it's not a substitute for long call.
plus if I remember if you do release to check in you lose LCO for the 1st day if something changes.
Its something but nothing spectacular.