How? You experiment on something for 5 years and then report. In my case of reading books: you read books and 5 years later you know what stuck and reread it in order to get the full wisdom out of it. It helped that I studied for 8 years and reflected on these kind of things every year.

Because without some shorter term studies you might struggle to get enough employers on board for a sufficiently powered long term one.

Good point. In my prior comments, I wasn't really looking at the pragmatic side of organizing studies.