Screening networking candidates

I just graduated from a college with a very tight alumni network, and now work at a BB. I am truly very grateful for all of the help I received from alumni (from the analyst to MD level) while I was going through the networking, interview and placement process. I really don't think I'd be here without them.

That being said, I was wondering if you all respond to every request for a phone call / networking session? Ideally I would like to do this and try to help out as many people as possible, but with such a hectic, jam-packed schedule it's often a bit tricky to accommodate.