Kinda depends on what you plan to do. I'm in academia. So whether I like it or not I have to live by the rule "publish or perish". I can volunteer my butt off, but if I don't publish some research I can kiss any jobs goodbye.

Also, "volunteer" is such a broad term. Doing what? Technical stuff? Cleaning? What did you do? How long? Did you have a mentor? Are the skills you learned applicable in another setting?

There are so many questions that go along with your initial question. Do you have a CV? What kind of jobs are you applying for? If you want, send me a PM and we can talk more.