Good question - I don't really focus on Ad Strength - I tend to focus a bit more on QS.
When setting up campaigns I typically do my best to match my ads with landing pages but sometimes the keywords I target are not specific to the same ads and landing page.
For example - If I am selling a diet product but my kw is "fitness plans" - sometimes the product encaptures a broad audience, and people searching fitness plans might convert on a diet product.
It can be tough to get it exact but if they still convert and reach my goals I run them and don't care too much about the QS or ad strength.
Below is a typical example of one of my campaigns that is running in the 5-7/10 range for quality score but it still profits well. As you can see ad relevance is low (which is an indication my KWs are likely not completely relevant) This typically happens I think when I run a more broad type of KW campaign.
If I find a KW that converts really well, I do sometimes create a specific ad group with its own ads and landing page that targets that specific keyword, and that can bring QS up to 9 and10/10 which results in a bit better ROI but nothing drastic.