The clever manager never views a project as an end in itself. Though the immediate goal is generally nothing more than building a product, you've got to use each and every engineering effort as a training camp for every member of the team. Move the team's competencies ever forward, always gaining experience as well as a product. You have to balance the risk of being late with the need to try new things. Constant incremental improvements are good.
Radical surgery is something a company can tolerate only occasionally.
They'll turn down dead-end jobs that bring no more benefit for the company than cash. Projects are selected and planned to insure that each one improves the business's competencies. Every company needs a certain amount of leading edge work designed to push the envelope. Mitigate risk by limiting the scope or importance of these projects, but do try different things. This means that everyone involved is committed to code recycling, from the CEO to the janitor.