When AF simply doesn't work or when it can't be trusted and when being finicky about where the focus point is I'll use manual focus and the magnified view.
I know this is a niche lens and f4.5 is maybe going to limit its use anyway but for me there's always going to be the odd focus target which'll tax AF to breaking point and for when that happens I'd rather use a lens with MF than realise this lens isn't up to it and have to give up and not take the picture or have the point of focus somewhere other than where I wanted it and obsess over that later, which I would do.
As you might have noticed I do like a cheap lens but the condition is that it has to be useful for my purpose and if going cheap I'd rather go MF with a cheap modern lens like the TTArtisan 50mm f2 which you can now get for £54 or the Pergear 35mm f1.4 at £81 or use a film era 28mm f2.8 which I already have but if I didn't I could get from ebay for £20-£30 assuming I already have the adapter. I do also have the Sony 28mm f2.
The cost does come into it for me as I'm not going to spend £1k + on a lens but I'd rather spend mini Sony G money on a conventional compact 28mm f2.8 if it existed than spend even a tenner on this Viltrox and want to throw it into the sea one day.
Many people wont miss MF and wont understand my objection to a lens without it but for me at least AF defeating things do exist and do attract my attention and I just know that one day I'd be triggered by a lens without MF and I want to smash it
Just for illustration...
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For this I wanted to focus at infinity so with AF I aimed at the wind turbines but AF just wouldn't lock on at all, no real problem except for the wasted time as I just manually focused. With a lens with no MF I wouldn't have had that option. Things like this happen at least for me and then there are the messy / AF distracting scenes and subjects and those situations when AF just doesn't know exactly where you want the point of focus. OK, sometimes you'd need to pixel peep to be able to see that the focus wasn't right but when you're an obsessive with a short fuse (and there are times when I have no fuse at all, blame it on my Celtic ancestors) these rare occurrences are best avoided.