When Should You Outsource Design?

i am a guy to whom design work is outsourced, so my view is biased that way. My clients had a technical collaboration agreement with foreign companies way back when, long over now. No employee left now who understands the design. So, in i come, with >40 years in the field, train the young engineers in the domain knowledge, solve current problems (which have mostly occurred due to ignorance of the design intent), modernise the product design... all at a relatively low cost. There are a few like me in the country, and indigenous clients have really no other option but to use us if they want to survive ethically. They do not have the access to global experts like MNCs have.

Two simple things:

When you do not have capacity to design inhouse.

Or even though you have capability, if outsourcing will be cheaper than making it inhouse, maintaining the same quality of design.

Design has been outsourced since time immemorial. Lots of business ventures might know how to profit from a ship, warehouse, factory, building, etc. But they might know the details of how to build such assets; and thus contract the design to A&E (architecture and engineering) consultancies and the like.

The team should keep in-house, those parts of a design that require the most important design considerations and outsource the less critical components. Naturally the outsourcer should be selected for his expertise with that component. Samples are usually called for and checked in-house for conformance and quality level. Also I might add; outsourced components should stand alone and not be tied in to the in-house parts. An example of this would be a component whose design cannot be completed until the in-house part is finalized. Failure to do so would result in delays by the outsourcer. I have seen outsourced components being made based on "preliminary" or "assumed" data, not working when it came time to assemble all the parts. As a result, parts had to be re-designed and that resulted in higher cost and delays.