[mozumder]

Yes. This is how it was done during the magazine era.

[rtpg]

Rarely. It was usually an ad agency that would do the actual deals to get things into magazines.

You could always contact a single magazine, but big corporations would let their ad agency handle distribution

[adrianN]

Did anybody advertise in 12000 magazines?

[mozumder]

If you include international magazines and newspapers, then yes.