yes, but
i think in most drafts, there are clear differences in rankings in the top 5 or 7 or even 10 (varies by draft). I think if one of those top tier guys are there, you would be a fool to pass on him in favor of a next tier player at a position of need
after that, i think the tiers of player grades gets larger so that if you need, lets say, an OT, you can probably find a OT in that tier.
i hear the Cards and other teams say stuff like "we had a 2nd round grade on him".
i suspect many NFL teams simply group players into those tiers (high 1, low 1, 2nd, 3rd, etc)
we get caught up internet rankings (88.6 vs 87.2 grade!) that NFL teams ignore (because assigning a precise number to an inherently subjective evaluation doesn't make it precise)