The consecutive sentences check assesses whether your text contains three or more sentences in a row all starting with the same word. This includes headings starting with the same word as the previous or following sentences.
Generally, a paragraph that contains many consecutive sentences all starting with the same word, won’t be a nice read. The words will feel repetitive and the text will lack flow. That’s obviously not great for readability. Worst case scenario: readers might get annoyed and leave your website. So, while an occurrence of three identical sentence starters may seem of little importance for SEO to you, keep in mind that serving your audience the best content you possibly can is the essence of a holistic SEO strategy.
The check will notify you when you have three or more sentences in a row starting with the same word, and it can show you where, highlighting the sentences in question. Try rewriting these sentences, so they don’t all start with the same word.
In some cases, you can’t avoid having several sentences in a row starting with identical words, for example for enumerations. Writers sometimes also deliberately start several consecutive sentences with the same word, to place more emphasis on them. In those cases, you can ignore the red bullet you get from this check.
In short: If the consecutive sentences check gives you a red bullet, make sure to check out where in your text this occurs. If you did not repeat sentence beginnings deliberately, rewrite your sentences and vary things a bit more to avoid repetitiveness in your text.