Structured data can help crawlers interpret the content of your site, but you have to consider where and how it will be useful.
Simply adding an
itemprop to one element is not enough, an
itemprop (item property) must be a property of some defined schema object and within its scope. Eg:-
<article itemscope itemtype="http://schema.org/Article">
<h1 itemprop="headline">The Headline</h1>
There the headline is the property of an article.
But another thing to question is whether this adds any value or semantic meaning to the mark-up, since it's an
h1 element, it can already be assumed to be a main heading within an article as per the html we already have.
This does not mean that structured data like this will always be redundant, in cases where you are marking up more things on the page, adding more detail than the html tags can provide themselves, then it may possibly be worthwhile. Though this can lead to messy complex mark-up full of extra divs and spans to hold scopes and properties and it can get confusing getting the structure and nesting correct.
If things are getting too complex, confusing and untidy another alternative to take this mark-up out of the html is to use Json data at the end of the page to hold the structured data.