Every company does their UX a bit differently. It all depends on resources available, are you a start-up or large company and the influence of your existing business-developer processes.
I worked for an ecommerce company and work were usually handed down from the top, in the form of “We need to redesign application X” or “We want a new application X”. My first response is always: “But why?”. Why do you need to redesign? Why do you want to build a new product? What is wrong with the current product?