There are a handful of cases where it's useful to use it to fish for a "good" or "excellent" as well, though those are vanishingly rare. A couple of times I've been holding a Innovation(2) x Great Strides(3) with a spare 14CP and just enough durability to hit Byregot's Blessing and then finish the craft, and in that case I'll fish for a "good" for my Byregot's. However, you almost never actually get a good when you're looking for one, and higher level crafting usually is planned enough that you're not going to have 14CP just sitting there. Even if you do, you probably don't have the leeway in ability steps to use an Observe. It's very situational.