It depends on what you want to scrape. The gold standard for flat surfaces is the Sandvik/Bahco 474 line, which measured .032” (.81 mm) .
A crucible tools curved scraper I have measures the same..
I also have a shorter Bakco that’s .6 mm and there isn’t much difference than using the longer,thicker ones.
But that’s too stiff for curved surfaces, and scrapers for profiles come in all thinnesses to acomódate special cases.
The really thin ones I have are only really any good for detai work on curved surfaces.