I honestly think the answer is they'll find it any way they can. The whole "hunt" for free porn is part of the thrill. So when people are horny and looking for sex, some may have less of a strategy and try whatever options are available at that urgent moment.

It might be best to directly ask people who are actively look for free porn and are not willing to pay for it, wherever you may find them. Maybe there is an overall pattern for all of those folks. I suspect there isn't because everyone has their own personal style. Some people like familiar routines (lets say search engines) and stick with them, or they prefer link links. Others get bored fast and experiment with anything that stands out, or actively seek new venues (which can be part of the thrill).