The Creeping Learning Curve: Every change made to the software, even those "trivial" little changes assimilated day by day by the design team, will be re-experienced, all at once, by each user upon first running the new revision. If your team of spends 6 months, and adds 1 feature each day, your users are going to be hit with 6 months worth of changes, all 180 of them, in the first 6 minutes.