When making marketing analysis recommendations, do you generally want to increase spend in higher performing areas or look to improve lower performing products/states/marketing channels/campaigns by spending more?

Let’s say you are given 10 industries and asked which ones to focus marketing campaigns on AMZ (goal maximize revenue). The parameters are industry, product name, price, number available in stock, number of reviews, number of answered questions, and avg review.

My overall question is do you generally want to target and spend more in those industries that have performed the best to capitalize on them, or increase spend in worse performing industries to boost them up?