H3 and H4?

I just found out that my theme is making everything on my sidebar an <h3> and <h4> so I have about 5 h3 and 5 h4, would you recommend me to delete this from the theme or just let it be / not prejudicial? I usually have 3 headlines and was using the H1-H2-H3-H4 headlines for each headline since they're always related.


Or maybe is it okay to have several h2/h3?

You can have as many h2-h5 as you like. It depends how you wage your website.
Most important thing = H1, later H2 and the less important thing should be in H5.

It's up to you and your strategy on the site.

H1 is the most important tag which should be used once to be on the safe side. Other tags can be used for headings, not an issue.

First and foremost an H tag is a styling tool to size headings, so H1 is a heading size. Like wise H6 is also a heading size, it is likely you may have more than one heading, and therefore more than one of each size.

It was always supposed that Google presumed importance from size. That being the most important heading is the largest H1.

Now this doesn't mean that you should remove all H tags which are superfluous to your desired on site seo, as there is also the issue of human readability. If you remove all sizing apart from your main heading you will have a wonky looking site.