I don't think teams seriously work with media mock drafts. But I think some do general mocks to try to predict where certain players they're interested in might end up, so they can try to target them before another team grabs them.
But generally speaking I think NFL teams put players in talent tiers. So say, we got top do the 3rd round grade in these guys, which ones are we most interested in.
Of course all teams have different rankings, and since Jerry Jones basically allows pictures of the Cowboys draft room come out after the draft and talks too much, I think at least one year they kept drafting players they had a late 3rd round pick grade on even in their late picks at least one year (I don't think they had a 7th round pick that year but even the 6th round pick was a 3rd round grade in their board). Which makes me question the board.
Of course, I've heard sometimes that happens to a lot of teams and they're all left wonder why everything is so different.
And honestly, I'm expecting more of that this year and more trading than normal, as the draft picks in general to me, seem less well rounded than other drafts and more specific... so I'm expecting teams to have a wide range of different grades on different guys this year and lots of surprises (maybe not round 1 but as they get deeper).