Letting a polish/compound sit on the surface is simply wrong. Obviously, your method has several fundamental flaws:
1.) If you leave your polish to dry out on the surface, you will instill micromarring with the fine dusty particles of dried product AND real tiny dust particles which are trapped in the residue.
2.) Polishes/compounds are not designed to be left on the surface. If your previous products didn't cause trouble, well, that's pure luck. The formulas may allow that, but it's absolutely not intentional, as no abrasive liquid is designed to sit on the surface after working it in properly. There is nothing in them which would need that.
3.) If you leave the residue on the surface, you can't control the working area precisely, because you have to go around the car, remove the residue, THEN check the whole surface for defects - which is a kinda snow-blindness. It is easier to focus on a smaller working area and make additional corrections as necessary.
4.) You shouldn't wait with removal - even when you are doing just a panel. The residue can be too dry when you remove the first working area on the particular panel. Divide a panel into imaginary, workable thirds/quarters on a door and 6-8 sections on a hood. Let's say a 20×20 inch area is manageable. Do your 20×20 inch working area, finish down the product properly, remove the residue, inspect with IPA or a prep fluid, refine it as necessary. Done. Move to another working area. Go round the car like this, then switch to a finer product and finish/finesse/jewel the surface.
5.) Compound dust is/can be very detrimental to health, especially when you let it dry. Airborne microabrasive particles/agglomerates/primer crystals and whatever may be in that specific carrier system can be carcinogenic, so you don't want to inhale polishing dust. If you wear a respirator when removing dry polish residue, it's fine, but I highly doubt that. Luckily, Optimum is not that aggressive, and more or less dust free, but that doesn't mean it is beneficial mountain air...
6.) There is a misconception in your head again, as a polish/compound won't *last* as they don't have any protective ingredients/qualities. If you just polish a surface, it won't *last * in the context of protection, because the surface is just polished, aka made smooth and shiny by abrasion, but not protected! It needs a wax/sealant for protection. All-In-Ones, like Poli-Seal or GPS have wax and/or sealant in them, and hence they are the only mechanically working abrasive liquids which need a little bit of setting time before removal. However, properly worked OPS doesn't have any residue at all.
If a polish/compound *lasts*, it is because you take care of the surface, don't cause marring and other physical damage. After polishing, the surface is virgin, bare and unprotected, and therefore the nonexistent protection can't *last* on it.
7.) Based on your description, the amounts you are using are huge. 1 hour just to clean the residues from a roof??? OMG, that sounds scary. When you're using a DA polisher, put 4-6 pea sized drops onto the pad for priming, and 2-3 pea sized drops for each subsequent steps. Optimum polishes have superior lubrication which ensures a constant, even buffing film, which is thin enough to let even the tiniest abrasive particles to strike it through. If you are just dumping, pouring product on the pad, you are hurting the effectiveness of the product.
Once again: 2-3 pea sized drops on a 5.5 inch pad and the working time should be around 3-4 minutes per working area. That way, the polish/compound can finish down properly even with a DA, and the residue will be just a very fine, almost glassy haze which wipes off with no effort.