That's the plaintive question on Brownstoner's forum. Short answer: Yes. But the long answers are much more entertaining.

• Most jobs take twice as long and cost three times more than you anticipated. Most contractors do three kinds of jobs: good, quick, and cheap. You can pick any two.
• Now you know why people buy 'move-in-ready,' as 'awaiting your custom renovation' should usually read: 'no economic incentive for potential 90% ruin of your personal life.'
• In my experience, 3 months means 5 if all goes well, 7 or even 8 months if something unexpected occurs. If you decode contractor speak into colloquial English, '3 months' means 'if all goes well, nothing weird happens, everything is in stock when I need it, and we have a bit of luck, it should take 3 months.' In reality, there's always something. We know how to predict but in reality there's always something in 50%.
• Unless you're a rock star who doesn't care what the renovation costs, as long as it's done on time, your job is going to be late for a combination of legitimate and not legitimate reasons. You can fight that, or you can get pissed off about it, but your energy is much better used making the assumption in advance that your job is going to cost twice what the contractor says and take three times as long, and planning for that.