[subjectHarold]

I would read the article and the source it links to again. If you do, it answers most of your questions.

Yes, the performance of the German economy was considerable. But the point with Schacht for all economic historians is that the German economy was operating under immense constraints. And what impresses is the way Schacht created endless devices to keep production growing despite these challenges.

And yes, they did measure things the same way. The way of the world today is to look at historical statistics and assume that no-one had a clue about economic policy before the 1980s (Germany was actually one of the most earliest adopters of stats in policymaking). But if you actually look at the primary sources, it is apparent that there was actually a great deal of knowledge. And, in some ways, that understanding was far more deep than today (as it was often based on practice and experience). As the article says, Schacht is an example of this.

More broadly: the job of the economic historian is not to work out whether things were "good or bad ideas". Historians realised many decades ago that the answer to these questions is subjective. You have to look at these decisions within the conditions that existed at the time.