I know the end of your reply is tongue-in-cheek, and a few people have made joking comments, but you are not wrong.
It's because construction workers generally used to, you know, work a full day. They rarely do anymore. And I'm sure Disney is also spacing this out due to spreading out the costs as well.
There is a small bridge (perhaps a few hundred yards) in my small New England town that had deteriorated, so last October they set up a detour and started ripping it down. Here we are, a year later, and still have the detour. Supposedly it will be finished within a month.
So it's taken a full year (with countless hours of people stuck in traffic, and accidents due to the poor detour route, etc.) to build one bridge that spans a few hundred yards (at most, it's probably less). Yet, although I drive by at all times of the day (7AM, 10AM, 1PM, 4PM, etc.) there is almost never any "work" going on.
It's just how construction "works" today. Especially with the construction industry having such a hard time in the economy, it's in their best interests to keep a project going and as extended as possible. It's ridiculous, but unfortunately that's the world we live in today.