Microdata and JSON-LD at the same time?

Question

Search Engine Optimization

On many of the largest, top sites, I see both Microdata and JSON-LD being used ubiquitously.
For what purpose is this being done? Are they not interchangeable? Is it worth implementing both formats? What can this positively affect?
if this is a stupid misunderstanding, which I doubt, then which format should be preferred?

Answer 1

Schema.org + OpenGraph - which syntax you will use (Microdata or JSON-LD or Microdata + JSON-LD) depends only on your project, how easy it is to load data.
+ People on the server wrote that Yandex does not accept the machine price tag for the goods.
+ JSON-LD is recommended by Google for company data markup.
Everything else depends on the project, if the front is on Angular, then I will choose JSON-LD, because it is so tight with content indexing, and there will be no place to hang Microdata.
And for all others 100% Microdata, because it is very simple and passes all validators.
Should I choose LD+JSON or Microdata? - here is another topic on the toaster on the same issue, but there are no answers, water.