i'm glad you still keep using your straights from time to time. Eventually it will all come together. I first got a Dovo in 1997 in Germany, on a whim. I didn't know about shave ready sharpness or stropping. I remembered seeing guys stropping in old movies and tried to do it on a belt. The results were terrible.

I decided to try again last year. After a year or so of woodworking, mostly with hand tools, I had become very good at sharpening. I decided to use my Norton hones to sharpen my old Dovo that I had been using as a letter opener.

It worked. I then found SPR, learned a lot more, and have progressed to the point where I can get a one pass shave in about ten minutes that rivals what I could do with my Mach 3, and without the EXTREME irritation that I always got with a Mach 3. And yes, I knew about and used good shaving cream and good preparation back then. It helped, but not enough to overcome the shortcomings of the Mach 3. I learned to hate those clogged, crusty, dull face scrapers. I have tried them again recently, and the problems remained.

It's taken about 50 shaves to get where I am, but it's worth it. For the first time in my life I can now get a great shave, without looking like I wrapped poison ivy around my neck. No more ingrown hairs or burning sensation either.
I'll never go back to Mach 3. Stropping used to take a long time. Now it's only a couple of minutes. Practicing on a stropping paddle helped. If I'm really in a hurry I use a DE. My Merkur slant is great, but not quite as good as a straight. All in all, it only takes me five minutes longer than the Mach 3. The results are well worth the time.
Keep using your straight. You'll get better, then you'll see what I mean. But if you use it rarely, you'll never learn. Use your straight every shave, just for five minutes on the easiest parts, then finish with a disposable. Eventually your experience will progress, and you'll get good at using straights.
Some things are worth the effort. I thought the same thing you did after the first time I tried a straight, "No wonder we've developed these cartridges, straight razors don't work. They're even worse than these Mach 3's." I hated shaving so much, I even tried to grow a beard, but couldn't stand it. I wish I had had SRP in 1997, it would have taught me how to use a straight and saved me over a dozen years of embarrassing irritation on my face.