He means all of the above. Well maybe except for the 124 (chromatic)
Interesting! My fingers naturally fall as 1234, so Iām still trying to figure out how to do 1-23 and 1-2-3. It seems that to do that I have to shift my hand towards the bridge a little bit to ācenterā 2 and then stretch 1 towards the nut and 3 towards the bridge. Iāve only got a few hours practice trying this so Iām definitely not used to it yet. 1-2-4 seems easier for me to finger than 1-2-3, but 1-23 is easier for me to finger than 1-24.
No difference between 1-2-3 and 1-23. Same thing different spelling for some reason.
I donāt think many would do 1-2-3 unless higher up on the neck where fret spacing was more narrow. If you were lower down with wider spacing the 1-2-4 is likely what most people would innately use - unless you are Paul Gilbert (notorious for 1-3-4)
Same fingers, different fret spacing. The ā-ā is indicating a fret between the fingers/fretted notes
This discussion is good. Weāre talking about a 3nps Major scale. The basis of Western Music, and we still donāt entirely agree. 
When I say 124, Iām only answering the original question. How to left-hand finger the major scale. Iām not discussing fret spans, just which fingers are applied to each stringās pattern.
I need to amend the statement where I said 124 for all strings. I was wrong. (āThat never happens!!ā says my wife. With sarcasm so thick, you need a knife.)
When I get to the B and high E, my hand switches to 123. I didnāt even notice until I played it with the intent to āproveā my initial comment (derp). Turns out my brain does what it wants.
At least from my quick analysis and watching my hand, it doesnāt matter where on the fretboard I am, nor how fast or slow Iām going. Starting on the 6th string first fret or the 17th (as high as you can go and still get the full scale in on a 22 fretboard.) My ādefaultā approach is the pic below. Even above the 12th fret, I automatically stay 124 until the B and E strings are involved. The same goes for descending and playing snippets of the complete scale.
I avoid lines that incorporate a 3 to 4 or 4 to 3 move. Thatās @Tom_Gilroyās fault. 
All this ignores special situations. As was stated earlier - nothing works for every scenario. With that said - if youāre transcribing someone elseās work and using 3-4 consecutively appears required, and it isnāt dead-easy chances are the person youāre copping didnāt play it in the same part of the neck.
Iām not saying, āDonāt ever do it.ā What I am saying is if your solution requires it, you may be overlooking something simpler. There is no getting around the fact that the 4th finger is the weakest. It is - and cannot be equal to the others. Especially when the 3rd finger precedes or follows it.
Can you improve it? Sure, the other three fingers will still be better in most situations.
Horses for courses. The above is just me and how I go about it. YMMV.
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Mmmhmmmm
Paul Gilbert. Colorado bulldog, 1 - - 3 - 4, may be the most comfortable fingering for many parts of it and required for his original fretting and sound, and IS NOT easy to play (and usually transcribed accurately because he has shown the fingering) Itās just difficult in general, but is accurate to how he plays it. He does have others with wide spreads like that too. But thatās well him, and it works for him.
This is the exact fingering I posted above. I donāt use it though. I use 1-3,4.
Iām happy you agree. 
I think we all agree that aliens are real.
If you donāt agree say Eddie Van Halen 10 times really fast.
Eddie Van Alien.
I rest my case.
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So 12-4 is great, 1-23 is relatively easy. Down the neck where the frets are wide 1-2-3 is difficult for me but I think 1-2-4 works. Higher up the neck there is a point where 1-2-3 works. I wonder if doing 1-2-4 and 1-2-3 makes sense, but Iāll probably do it for a few months and see what happens next.