As you get more skills, and in particular as you get Byregot's Blessing, you'll find that the bulk of your quality is made by your final touch because of IQ stacks in general and Byregot's Blessing. Therefore it is quite worthwhile to use Observe a few times to ensure your last touch hits at least a Good (+50%). Of course, you shouldn't use Observe so that you can no longer use Great Strides (+100%), but hitting a Good on your last Byregot's Blessing or even Advanced Touch can mean the difference between 75% HQ or 100% HQ. It's not a big deal early on when you have no real way to build up a large number of IQ stacks let alone get Byregot's Blessing.