Instead of tolerating this condition, get the work done by an Independent Professional. Occasionally such assignments can be converted to full-time employment. Workloads are sporadic, seasonal. There are jobs that are not full-time by definition. Rather than shuffle and disrupt a workforce to accomplish tasks that are sporadic, it is better to bring in temporary help.
Growth occurs in unpredictable spurts.
Unlike the regular ebb and flow of work that can be planned, e.g. holiday selling seasons, there are situations in which work comes in sudden spurts. Greater than expected success for a new product is an example. This is an obvious opportunity for short-term help from the outside. Fresh thinking, new ideas are needed. It is human nature to become accustomed to familiar surroundings and situations, and to overlook opportunities for improvement.