I do use SemRush, but I do not rely on it. The reason is that earlier, I used it for a mega project. However, it did mess up. So I decided to use it as one of the tools, and not the main tool. For main tool, I now consider Google SERPs, search console, keyword planner and obvious Google auto complete. But that is not it. You also then need to match it with Google trends. After competitor research, you will then get a better idea of how to use it.
Also, if your website it new, or is not ranking, my suggestion is to not go for high volume keywords. They are luring, for sure, but they will mess you up. Instead, prepare a content strategy first. And make it a mix of all kinds of keywords. You need both, target audience, while also building trust within them.
That is how it should be now (considering keyword stuffing now just does not work anymore). It is the context and intent you will be hitting at.