Like any specialty lens, you don't want to saturate a series of photos with tilt-shift. It just depends on the overall look you're going for. Some clients love the softer, more ethereal look of the tilt-shift, while others may want a sharper finished product. I always shoot with two bodies. One always has a tilt-shift on it and the other one always has a standard prime. This way when I am shooting a particular scene, it's simple to shoot it on both and decide later what worked best.