Your electronic system may include 3rd party subsystems such as GPS, WiFi, Zigbee, and Telco-connected radios. These subsystems may not be stable products, creating ongoing support and compliance issues. Instability is caused by firmware upgrades, hardware changes, parts and subsystems going obsolete, Telcos who make small but disruptive changes to protocols, power requirement changes, and so on. Discontinuity of supply may involve rework of your product hardware and firmware. When product instability occurs it sometimes requires time, and deep technical analysis to determine the cause of the symptoms, and then a development period to resolve the issue.
Subsystem instability is a very good reason for working with a developer in the first place, rather than hiring individuals for a limited period of time. If you choose a developer who is currently developing with the kinds of subsystems that will be in your system, the changes are he will identify and resolve your support issues before you realise they exist. At the very least he will have the familiarity, diagnostics, tools and environment to be able to re-create and resolve the problems.
Developers are exposed to many components and products. They are like chefs: always looking out for the latest ingredients and methods. This is a vital and necessary part of their business, and essential in the early stages of product concept and implementation. Only developers, or large companies with permanent development teams, can simply know enough to make good technology decisions.