If you can calibrate your own scanning process, you can make it work for you, but a contact sheet takes out all the variables of scanner focus and unwanted sharpening.
Where I discovered this problem was when I took my color neg film to Duggal a few years ago (otherwise a first-rate New York lab), and ordered contact sheets only to discover that they had switched to making digital proof sheets scanned in the sleeves and obviously sharpened, because there is no way to make a really sharp scan or contact print from a negative in a sleeve, and once any kind of digital sharpening is introduced, there is no way to tell if the original neg is sharp without inspecting it directly.