If you already know 4LLL after 2 years, you should learn full PLL and 2 look OLL (which is part of 4LLL) and be more efficient in F2L and the cross, when I was in sub 40, my problem was the cross and F2L, after I learned to do the cross on bottom, and be more efficient in F2L i was more than sub 40, and also be more fluid in your solves, try not to pause. Be not just fluid in Cross and F2L, also be fluid in last layer as I talked about using 3 look last layer (Full PLL, 2 Look OLL), and finally try to be faster in your transition from Cross to F2L and also F2L to Last layer, so the least in your priority is spamming TPS and learning full OLL as those are not needed until you reached sub - 20 or so.
At that speed, knowing 2lll will at best help him a second or two, and at worse make him slower by a second or two. Until your recognition for 4lll is close to instant, learning 2lll won't help.
If he doesn't know F2L, what's the reason to learn 4LLL? order : Beginner's method -> Transitioning from Beginner's method to CFOP by learning F2L -> 4LLL (2 Look Oll, 2 Look PLL) -> 3LLL (Full PLL, 2 Look OLL) -> Efficient cross and F2L and Cross to F2L transition -> 2LLL (Full OLL and PLL) You can do the 3LLL and Efficient F2L + Cross and cross to F2L transition steps at the same time to be faster than sub 40.
I learned 4lll before F2L because to was hard to learn. And I think that development strategy sucks. People are slow because they're F2L and LL recognition is bad, not because they know 4lll instead of 2-look. I don't even know PLL but am securely sub-20. I would reccomend learning PLL before then, but it proves you don't need 2-look. Here's my progression for a CFOP solver:
Learning to solve a cube
Learn beginner's method and practice
50-1:30
Learn CFOP(F2L and 4lll) and practice
45-50
Improve cross+F2L efficiency and practice
40-45
Improve cross+F2L efficiency and practice
35-40
Improve cross+F2L efficiency and practice
30-35
Improve cross+F2L efficiency and practice
~30
Look at your LL. If your recognition is very quick and pauses are virtually nonexistent for LL, then start learning PLL. If you still have trouble with recognition, then don't. Also improve cross+F2L efficiency and practice.
20-30
If you haven't learned full PLL, then reevaluate your LL. If you now almost pauseless with 4lll, then go ahead and learn PLL. If you've already learned PLL, then start learning OLL. Also improve cross+F2L efficiency and practice
15-20
Improve cross+F2L efficiency and practice, start learning OLL after PLL
10-15
If you're comfortable with 2lll and don't mind learning algs, you could consider learning some more alg sets like WV or COLL if you want, but not necessary. Improve cross+F2L efficiency and practice
Sub-10 and beyond
Improve cross+F2L efficiency and practice, you can keep learning algs if you want
Get the pattern? Waiting to start improving F2L and instead learning 2-look at 30+ seconds is detrimental(even more so at 40+), and will require a LOT of catch up work later when you know 2lll, have bad recognition because you learned it super early, and your F2L sucks because all your practice has gone into algs. Plus algs are easier to learn as a faster solver than a beginner. Algs don't help that much, and the improvement is basically 0 at 30+ seconds.
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