Good search engine optimisation involves many different aspects, some of which are visible to the visitors and some are not. The visible aspects of SEO efforts include the URL, keywords stuffed within the main body, headers, and on the other hand, the invisible aspects are site speed. This does not imply that they are not necessary, and as a professional SEO agency or SEO specialists, we work hard to cover all the aspects to meet your needs, and that includes technical SEO.
Still, thinking if you need technical SEO help or not? You need to spend some considerable time in exploring all the problems sites face that are similar to yours, every day.
Think about having a website that redirects visitors that are based on their area to your site. For instance, if you have two websites, one to target the UK audience and others to target the French audience, they will land on the respected websites accordingly. This is one of the best ways to grow the conversion rates, but for the search engines, this might be problematic. In reality, they might see your UK website, which can damage your rankings.
Search engine prefers those websites that are fast and user-friendly. If your website opens slow and takes a lot of time to load, Google will notice it, and this, as a result, could diminish your website ranking.
Probably you have moved domains and want to redirect the visitors for some time as you perform maintenance. Search engines won't take it in a good way if you are not using 301 and 302 redirects properly. All other redirects should be put off the limits, and if you tend to use it improperly, then you can expect to see changes in your scores.
Are you using wrong header codes? Both users and search engines likewise need solid header codes to view your website pages. So if you fail to optimise your website in this regard, then you are overlooking an important aspect of your rankings.
Nothing happens magically; you need to make an effort and spend time in constructing a good site architecture to avoid facing issues. Google won't crawl every section of your site. If you are wasting Google's time on those pages that you care about, your ranking will suffer due to this issue.