About to start house construction this week, what should I watch for? [Ichijo Komuten]

I'm about to start on the foundation construction and, so far, I have not hired an independent inspector (reasons below). Is there anything I should watch for myself in order to make sure it all goes well smoothly?

Is there anything in your house you wish you had caught earlier on during construction? A misaligned panel, leaky gasket, cracked foundation (!)… ?

Why didn't I get an independent inspector?

My salesperson is the branch manager (店長), which every Japanese says it's super lucky because they have full authority to assign who will work at your house. And indeed, this guy assigned us an amazing architect. This branch manager is also a local, born, raised and currently living near where we are building our house. He has built many houses nearby and have a lot of experience with local contractors. So he told us not to worry about construction quality because he made sure to assign us a good construction manager, inspector, yada, yada…

So we felt somewhat safe not hiring an independent inspector, which I hope we won't regret. The full independent inspection was much more expensive than I expected (close to 400,000 yen). But the main reason is that it would require in-between days for the inspection to be conducted, delaying the construction. I know "one week delay is better than a house with defects", but I am committed already to a fixed rate loan and construction is scheduled to be finished right before the usual Bank of Japan monetary policy meeting in September. So each day of delay means a huge chance in increased interest rates.

by Alive-Arm-7999