Take-home projects are not the best way to judge skills (atleast in their current form). In the future, there would be some centralized solution so we don't waste time again and again.
My "centralized solution" is my career. I've successfully done a lot of hard work, I can speak intelligently about it, what more do you want? (generic you, not OP you)
The problem with "I can speak intelligently about it" is that many unskilled applicants can also do it. So this shouldn't be the deciding factor.
I never met anyone that can talk well about code, that can't actually code. I met plenty who like to throw hip new technology buzzwords around without actually having good reason to use new technology.
We are trying to do same i.e. streamline the process. I do both take-home projects as well as pair-programming during screening. Take-home projects give me a big picture about candidates' ability to solve problems with software whereas pair-programming interviews tells me about his ability to think in terms of code at deeper level.
I fear a centralized solution, if only because Credit Bureaus are the same idea for your money.
The equivalent for jobs wouldn't be better.
create a commonapp style application process? one project, multiple companies, and companies can add their supplementary challenges or something
That assumes that you know how to test and judge engineers. I think the larger issue in engineering interviews these days is that we simply don't know how to effectively separate good engineers from the bad, and given the nature of our job there is a sometimes significant lasting negative impact of a bad/messy programmer.
In addition people are better at different things. I joined a startup recently. The code is well organised at the top level, and the logging was superb. However the architecture was terrible, horriby overengineered. And it looked like a Java programmer doing python - camel case instead of underscores (well a mix just to be inconsitent). Joins done at the application level rather than the database. And just doing way more work that was needed to calculate something.
It's an interesting idea.. something like fizzbuzz style take-home.