I think the definition for a project and the experiences you have listed actually complement one another. What I mean by this is that in the beginning a project created with the criteria listed as having a defined beginning and end along with other related goals. Having a project placed on hold does not interfere with this definition. What was once clearly defined to start is now being redefined. As for your other question, I do believe projects should be canceled to give more resources to other teams. Most companies care about one thing, the bottom line or in other words, profit. The role of a project manager is to realistically assess and allocate the resources of a project. If this realistic assessment is that a project will not bring in as much profit as another project given the same resources, then you can guess where those resources will be going. Also keep in mind that a company can only maximize profit in this manner as far as consumer demand allows them to do.