You seem to be saying 15 years experience means you should have a network that will be good for jobs, so why bother applying to ads?
What if you recently changed specialization, or moved city or even country? What if it's been a few years since you were in actual employment, you were working on startups, or had a career break or whatever. What if you have way more than 15 years experience. And so many other situations, which might result in your network being limited or not that good for finding the kind of work you want.
The point is, if you apply to advertised jobs, it's a numbers game.
What if you recently changed specialization, or moved city or even country? What if it's been a few years since you were in actual employment, you were working on startups, or had a career break or whatever. What if you have way more than 15 years experience. And so many other situations, which might result in your network being limited or not that good for finding the kind of work you want.
The point is, if you apply to advertised jobs, it's a numbers game.