I've seen a _lot_ of folks put multiple separate `setState` calls in a row, one for each field they want to update. I make sure to point out that it's nicer to read if they're collapsed into a single call, but it's a very common thing.
Folks learning React will do that at first, because they don't know better. We _have_ caught that in code reviews, taught them not to do that, and moved on.
But yes, it is an actual thing I have seen people (coworkers and otherwise) do, not some made-up problem.