More often than not you're using an inch or less of a straight bladed razor. On your cheeks and portion of your neck you might just get away with 2-2.5 inches, but I often find that to be more likely to end in a cut or razor burn because you're shaving round flesh with one of the sharpest things known to mankind.

The art of wet shaving will teach you thoroughly that patience is a virtue, and less is more. You rush a shave, you get cuts and razor burn. Use too much pressure? Cuts and razor burn. Too much blade? Cuts and razor burn.

At any rate a smiling blade takes no more time than a straight edge. In fact I find it beneficial to have a smiling edge to get into the hollows. YMMV.