I actually just got out of a period where I was looking for a new job. 66% of the offers I got originated from a message I passively received from a recruiter in LinkedIn, including the offer I accepted.

So I would say using LinkedIn in this way seems to be working well: setting up your profile as well as you can, that should make it so you receive endless messages from recruiters. Then when you're looking for a job, just respond to the last messages you got.