Observe is fine. You won't always have something else to do while waiting for your Great Strides to hit a Good/Excellent and Observe is still the cheapest way to do it. Just keep in mind if you get into a situation where you have to use Observe 3 times in a row you're probably doing something wrong with your CPs, unless you're only level 20 or so and have nothing else better to do with your CPs.