A lot of really good Landscape Photogrpahers, like Thomas Heaton for example, swear on using Manual Focus for Accuracy and Sharpness. I only use Manual Focus when I really have to, what is not usually the case.
And that is not because I have no clue when it comes to focussing manually, I am actually quite good with it when I shoot with one of my old Analog Cameras. Their Split Prism makes it quite easy though.
The major Problem is that all of my Lenses have STM Focus Motors. That is Canons Stepper Motor Technology. When you try and focus those Lenses manual, your Focus Ring has no hard stops, as it is Focus by Wire. Because of that, there is also no Distance Scale on those Lenses, what is no real Problem for me though.
My Problem lies more in the Cameras I am using the most. My old Canon 100D was really not set up for Manual Focus, it could confirm Focus with a few Lenses, but it would never tell where it actually thought the Focus was. My Canon M5, while having Focus Peaking and Magnification Options (5x and 10x) during MF Operation, I still do not use Manual Focus that much.
The main Reason why I do not use Manual Focus is that the Auto Focus System of my Camera is good enough for me. Actually, it works really really good. It is also way faster than I would ever be using MF. And if it can not find Focus right away, like when I am shooting towards the rising or setting Sun, I just have to select a focus point with Canons Touch & Drag function while I still look through the Viewfinder. And that only happens when I have Face Selection and Tracking selected in the Focus Menu.
And while I understand the appeal of Manual Focus and also those who use it, it usually is a bit more accurate, I do not really use it all too much. Except for when I am shooting HDR or Panoramas. Then I first use Auto Focus and then switch to Manual Focus so that the Focus stays where I want it.
Robin Ho Fotos 
I agree the Canon lenses are not easy to focus manually for just the reasons you state. Can’t even tell which way to twist the ring. I rely on autofocus, perhaps too much, because my eyesight isn’t that good. My pictures are nearly always a surprise in composition, and not necessarily a good one.
For the old lenses … well having a ring with numbers on it and a depth of field range marked off gives an easy way to pre-set focus for mid to distant range without having to rely on failing sight.
But there is definitely room for improvement in automatic lenses.
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Canon Lenses focus closer by twisting the Focus Ring to the Right and to Infinity by twisting to the left. But I always mix those up and get confused. And with lenses that focus internal (ie not moving in and out) it’s hard to know when you’re at infinity or at the closest setting.
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The biggest problem I have with autofocus, btw, is sky shots. Whether getting some interesting clouds or spotting a bird or plane the AF on both my Nikon and Canon will hunt endlessly in the infinity of the sky, never finding it. A nice labeled focus ring could be twisted to INF in a fraction of a second.
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That’s true. A lot of Cameras struggle with that. So yeah, Lenses with distance markers are better for that.
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