Camera-shake, lens flares and so-forth are sometimes best added as a post-production step. If all you want is for the entire image to shake, it’s considerably easier to do that later than to do it during the first render. Otherwise the director says, “I’d like it to shake a little less… can you do that? By tomorrow morning?” :banghead:
Oh, you might say, “but that wouldn’t be the same! Things in the foreground should move differently!” And yes, you’re right. And yes, it might matter. But Star Wars I actually shipped to theatres with a stadium full of colored Q-tips. No one noticed (that one-second shot…) until it was pointed out in a book. (It’s since been fixed.) There is definitely a “point of perfection” beyond which you enter the realm of diminishing returns. The simplest way to reach “good 'nuff,” while retaining flexibility, is what you want.