I wouldn't count on that to the extent of submitting less documentation than you would otherwise.
The various Schengen countries are supposed to follow a common rule set when deciding visa applications, but the rules are phrased very generically and leave a lot of room for being applied in different ways by different consular services. The few hard rules there are don't mention anything about visitor visas for the USA influencing the decision, so a blanket claim that all Schengen consulates will react to them in the same way is almost certainly false.
What is generally true is that the same facts about you and your circumstances that made you qualify for a US visa are also likely to make you qualify for a Schengen visa, since they look for broadly the same things. So document them with the same care you did when you applied for the US visa.
It would be different if you had legal residence in the US -- that would make it less likely that you're going to overstay and become an illegal immigrant, since most people would prefer to be legal in the US over being illegal in Europe.
But a mere visitor visa will not have this effect. That only gives you the same opportunity to immigrate illegally to the US that you would get in Europe. And most European consular officers would easily be able to think of reasons why you would prefer being an illegal immigrant in their country over being an illegal immigrant in America.