Our philosophy in dividing workload is simple: If the balance of frequency and complexity dictates that in-house performance is more efficient, we will develop the skill sets, train our engineers and assume the task.
This maxim works because we have the technical resources to do this.  Additionally, and importantly, we developed and follow a Task/Frequency program that ensure we are extracting the desired efficiency and quality from each task.
What does this mean to you? We don't guess at which way to complete our tasks. Contractors, when they are used, are held to a rigid standard of quality and frequency. Contractors know, if they don't perform, we have the resources to replace them, and we will. We are putting our reputation in their hands.  We will assure that they enhance it, not damage it.