When you commit to a project, it’s a real commitment, not a partial commitment. Here’s what a real commitment means: that until you make another conscious portfolio decision, you commit to funding this project. You commit to assigning the necessary people to the project—and only to this project. If the project needs something else (space, capital equipment, desks, whatever), you commit to delivering that to the project.
When managers don’t fully commit, they revisit their projects again and again. This creates both management debt and project technical debt. They also create capacity debt because people (managers and technical) can’t improve their capabilities when they’re overburdened with too much work.