If keywords are initially closely related, for example, sneakers of different brands, you should choose “Strong”+”Strong” or “Strong”+”Weak” so that only the closest synonyms are combined into a cluster. As a result, you’ll get lots of clusters to use for separate pages or specific categories.
In the case of various products and services, for example, you are collecting keywords for a multi-product store or medical center with a full range of health-care services, it’s worth selecting “Weak”+”Weak”.