The eye takes in about 6MP at normal viewing distance (where the viewing distance is the same as the diagonal of the image). Offset litho and laser printing requires double this for over-sampling. Above that, whether an image is 'sharp' or not depends on how it is being used.
If you are shooting for advertising on 6-sheet or 9-sheet boards, such as AdShels, which are used in the UK for bus shelters, then people walk right up to them, so the viewing distance might be 70cm. For that, your 36 MP will come in very handy. However, it's very unlikely that you would capture an advertising image without using studio lights, at which point you can be virtually throwing the camera in the air (or having the subject jump in the air) and it will still be sharp.
If you were to use a street photography image for an ad campaign, you would almost certainly want both motion blur and grain in the image, to cue the reader that it was a walk-around shot and not a studio shot. More likely you would carefully set up the pseudo-walkaround and add the blur and grain later.
Personally, I'm finding that following the 1/focal length rule produces entirely adequate results handheld. They don't appear blurred at any printable resolution, until you compare them with the razor-sharp images you get with deep focal depths and 1/2500 second exposures under studio lighting. However, this has been true on almost every camera I've ever owned.
What I actually struggle more with is getting the point of focus absolutely on the eyes, for portrait shooting. For this, I would rather increase my focal depth if I'm prepared to increase ISO, rather than increase the shooting speed.