Sounds like organizational failures all over the place, not the fault of contractors.
I’ve never been on a job site where the guy handling the software for the last 10 years understood it worse than I did after the first six months.
Bring in contractors for a codebase 10+ years old? Yeah, the current team is not working properly from management perspective. So either the manager doesn’t understand what they do, or the team is incapable of communicating to management what they do, or the team is shit.
So there are plenty of instances in which a contractor will roll in, throw something patchwork together, dump it on the client, and then leave me to support the rickety piece of crap for the next five years
So management and current team let in garbage code, that means there is no working review process. If the team didn’t establish a review process they don’t know how to work with modern methods, if management prevented it they are just incompetent.
Would the $300/hr for a year of fussy support been more valuable if applied to a $40-$80/hr on-site tech who stays with the firm for the next five years?
I don’t think adding another employee to an environment with broken communication and no code reviews will improve anything. And contractors can’t magically fix your broken org.