Inherent in the responsibility of a manager who gets work done managing others is to provide training opportunities. Sometimes a particular team assignment or project requires all contributors to have the experience to execute. That said, there is usually an opportunity for training and development in the delegation process.
The team gets better, stronger and more productive the greater the skill and knowledge of the team members. the manager has the task of not only delegating project assignments but to look for opportunities to assign work that will provide a chance for a particular employee to learn and grow. This is really a core competency of a strong manager. When planning a project and the action steps required, take the time to look for development opportunities for members of the team.