One of the key ways to keep work moving forward is to avoid working on too many things at the same time. Ideally, a person should finish what they’re working on before starting anything else. Similarly, a team should complete the work item or ticket or story (or whatever they call it) they’re working on before picking up the next one. At a larger scale, a software delivery organization should limit the number of projects in flight concurrently, and strive to “stop starting and start finishing,” as David Anderson put it. That’s what portfolio management is for (among other things).