New member here.
i don't know much about Meguiars Ultimate, but I suspect that you are simply filling in and hiding the swirls temporarily with your wax, which once broken down after a few washes, reveals what has always been there. Meguires scratchx or swirlx is okay for minor touch ups, but to clean up your paint properly, you need to polish it out with a decent orbital buffer. Polish might be sufficient, but if you have some scratches, you may need to move up to a compound. My set up is a Porter Cable 7424XP with Lake Country flat orange and white pads and Optimum compound and polish. I normally do this every spring, (winter can be brutal up here) but sometimes twice a year. it is a full days work to do it properly, and finish up with wax. For finish (wax), I have been using Zaino for about 16 years, and love it. Long lasting protection and amazing shine, can be used on plastic without turning white, and can apply multiple coats in one session. My black vehicle is pristine even after 3 years, and when I am done polishing, it looks BETTER than new. If you don't have or want to invest in the tools, seriously consider having it done by an auto detail shop. You can find coupons online through Groupon or other coupon offerings in your area. Then, just ensure you maintain it, which is a good segue to the next section.
How long you keep swirl free also depends on what you are using to wash and dry. I have a very good and plush microfiber mitt, and use the two bucket method...one with soap, the other with clean water (both having grit guards at the bottom). i soap up, wash a section, then rinse the mitt in clean water, then back to soapy bucket. I also rinse vehicle well to remove lose grit before starting, and then spray soap on each section before the mitt touches the surface. some use fancy sprayers...I got a small hand pump sprayer at a hardware store called Lee Valley...does the trick for me. There are a ton of soaps out there, and I figure as long as your using a popular brand, you should be good. But don't go using your dish soap. You want some lather to provide a fine barrier between your mitt and any grit it has picked up and your paint. Finally, drying. I dry most my vehicle with a dedicated leaf blower and only touch up spots with good quality waffle weave microfiber towels. This has two benefits: first, less contact with surface means less swirls, and second, it knocks out all that pesky water that likes to sit in the nooks and crannies, and come out only after you start driving, leaving those unsightly drip marks.
All this makes a huge difference, but requires some dedication. All this stuff can be found at popular on-line auto detail stores.
Hope this helps.