As some people might recall, when Grand Theft Auto IV first released, Rockstar held a promotion in which anyone who completed the game to 100% within the first week would receive a physical key to the city. (They later, to my indignation, relaxed this requirement to within the first two or three weeks, either because their Social Club servers we had to use to confirm the achievement were totally busted, or because they realized people like me were blowing off a week of college classes to drive taxis for Roman.)
That was the last time I ever had to rely on an actual strategy guide, as I was on a time limit to shoot every stupid one of those two hundred pigeons before the week was out and I couldn't wait for any online walkthroughs to appear. Had to go back to the store and pick up the book. It was basically like paying for assistance DLC.
I got the key, though.
On the larger subject of strategy guides, however, they can be great! My bookshelf still contains a modest collection of classic Versus Books guides.