Have National Rail Operators been generally sucessful at building and operating Regional Rail Services?

Before we get to far I'm using "Regional Rail" to refer to pretty much everytghing that is mainline rail (not separated metro or rapid transit networks) but not intercity services.

I know in many countries it is not uncommon for the national rail operator to also operate and build (or at least be involved in building) regional rail services. I was curious if anyone could offer any insight on whether that model has been successful or whether it has actually been detrimental to these services and you would prefer local municipalities to take initiative?