I must have missed this thread back in October, but I'll add my two cents here:
A lot of what you are running into is the trades. Work can't happen on your house if people don't show up to do the work. If other people are waiting for the 1st group of people to finish their job, well, they ain't gettin' paid until the job is done (if they are lucky, they actually are on 90 day billing periods!) which really screws the trades around.
But in the end, the builder can only do so much. One thing you have to realize is that you can't simply pick up the phone and call a framer to frame a house right now... THERE ARE NONE. There is a huge labour shortage in Alberta, and it's only going to get worse. And once a company has the business of doing the trade work for a certain house, they are pretty loosey goosey on the schedule if they can make more money elsewhere, they are going to that job first. Or again, if they are held up at your job, back of the que your house goes and they move on where construction can be moving forward.