This sounds like something I tell people when they ask me when I should buy a computer and my answer is "next week". The next computer will always be better than the one you can get today. However, you can't really use a computer you haven't purchased yet, so it's not really better in practice.
Well, why? If they are using more material than necessary, or wasting time due to different soldering techniques, why do you care? What matters is that the end result performs as expected. If they are not hitting their production or profitability targets, it's their problem.
Elon Musk says the quality has vastly improved and continues to improve. That means today’s Model 3 is worse than tomorrow’s and yesterday’s is worse than today’s.
That's true of almost all products, and certainly of most cars. A 2017 Honda Civic is better than a 1977 Honda Civic. But you can't drive a 2017 Civic in 1978.
