BJ, you're not that empirical, huh?
First you have to use the OOS to understand how it will "disappear". With different explanations and interpretation you may slide into misconceptions and the final outcome might be totally different - and this can cause *surprising moments* and in some cases dissatisfaction.
So, if you have your bottle of OOS, grab it and hurry to the car armed with a MF or foam applicator and start doing it.
OOS will flash VERY quickly. It is thin like water, so it won't pull a grimey film over the surface. No, you don't have to spritz the target area once more if your applicator is already primed. Priming: 2-3 pumps on the app.
Start to apply it. It will discolor the surface, as leaves a rainbow-like trace which fades away almost immediately. If you overapply it, it will evaporate slower, but the final outcome will be the same.
You have two choices:
1.) Apply it just like a QD. Wipe it in until disappears. This happens fast.
2.) Just cover the surface and leave it. It will evaporate quickly - so this happens fast too.
Try both to know (the basically nonexistent) differences.
Optional: you go over the area once again, or you can knock down the heavily applied spots. Done. Really.
Applicator reload: when you think that the app doesn't work any more, because you can't see the trace, just slow your arm speed, or hold the app in one place for 3-4 seconds. Lift it up and when you still see the wet spot under it, it lays down a sufficient layer of product. When you move the app really slow, you'll see the faint trace of the OOS behind the applicator. If this trace vanishes, spritz again once. You can push the applicator itself to force more product out of it. Push it, release it and apply further.
Cover the entire car. Finished. Final remark: doesn't matter which movements you use, just make sure that you covered the area properly.