A team is only as good as a team without its most valuable member. Team members get sick. They take vacation time. Emergencies happen. There will be a time when highly valued members aren’t around to help, but if a team is well organized, efficiency shouldn’t be affected. If a great employee leaves the team in the middle of a project, the team must be well-structured enough to pick up where the resigned employee left off. This is done by never depending on one person. Employees should be cross trained in more than one position in the case they have to take on new responsibilities. Many companies have their employees complete training rotations. Money invested in employees is money well invested for the company. This ensures that the company has highly skilled employees ready to take on more than one role if required. Of course no employee should be spread out to thin, but there is always value is cross-training employees when possible.