Originally Posted by sailingfun

There are a variety of reasons for this. Some have to do with special airport and aircrew requirements. Others have to due with automation and the fact that next day trips are worked manually.
The key reason however is to provide a better quality of life for reserve pilots. It certainly would be possible to set up a move up system like the flight attendants have that could run the day prior and even same day as trips drop into open time. It will however result in absolute crap for reserve pilots in terms of trip quality. Every change in how we assign trips has ramifications that are different for each seniority segment. I don't ever plan on being on reserve again but don't mind granting this benefit to reserve pilots.