The build-or-buy question gets asked too early, and usually before anyone has written down what the software actually has to do. A platform chosen against a vague brief tends to get re-chosen within a couple of years, at a second round of cost.
This coverage sits mostly in the stretch between selection and go-live, where implementations quietly lose their schedule, and on the ownership question that follows delivery — what has to exist inside the business, in documentation and internal capability, before a vendor can reasonably step back.