Normally doing certain things like being a closing out a baseball game by committee, rarely seem to work well in the long term. However for mentorship I think its a great thing. A few people I know going through the PhD process seemed to be more than satisfied to just be mentored by their PhD advisor alone. I think this is dumb as hell personally, I tend to opt for the mentorship by committee option. And I'm not just talking about my own PhD committee, I've expanded my net to other professors and even those outside of academia.
My advisor's advice is invaluable and very helpful but much of the time it can just be limited to the realm of my project. Sometimes mentorship in the areas of my future and professional development can be lacking. These are the things that rarely come up in our meetings, he's much more interested to see my most recent data, and rightly so because it affects his bottom line. But from time to time, throw a bone at me on what I should be doing or improve upon or opportunities to look into that might help me on later down the road. And that's why I'm tossing my fishing line in other ponds, I'm trying to catch more than what you just have to offer.
Smartly, I have developed a great rapport with my PhD committee members and keep in touch with them about what I'm doing and should be doing in professional life, not just my thesis project. Also I have reached out to people and industry, policy, and regulatory bodies to get their perspective on what they do and what they value about their jobs. Why would you reach out to someone who works at the FDA? Simple, there aren't that many tenure track jobs out there homey. You gotta keep your eyes out for any opportunity and it provides a fresh opinion from my advisor and committee who have been locked into academia forever. How did I meet these folks? Easily in fact, I just walked around some meetings and pressed some flesh and shot the shit. I showed interest in their work and asked if I could contact them in the future. Business cards were swapped and emails were exchanged.
Its interesting to know what areas of industry research are drying up and which ones are blossoming, what the new regulation is coming down the pipeline, or what inspectors are looking for. I enjoy chatting with these folks to see what they do, what they love about their jobs, the shittier aspects of their chosen profession, and what are critical skills needed to do what they do.
So if you want to just take everything your advisor says as gospel and not seek out alternative advice, go ahead. Not me man, I'm always seeking out new perspectives.