Footfall counting helps you understand the volume of customers you are getting a day, the beginning of your funnel. Sales data shows you the end of your funnel; it shows what customers end up buying. If you know how long customers spend in different areas of your store, then you have more awareness of what products customers looked at first and considered buying. You can see where they go when they enter your shop and where they are stopping. Comparing this to sales data for those products helps you refine product offerings. This knowledge allows you to experiment with messaging and displays which in turn helps you find out what results in increased consideration time and browsing, ending in greater sales volume.