>use the small windows of time we look at our phone

again, it's not a small window. It's six hours. That's almost half your waking day. People spend virtually their entire leisure time rotting away on low quality entertainment.

>will me spending my time learning OCaml help me land that job

that's a pointless question for one you never know if something will land you a job, new opportunities don't open up before you do something, secondly the relevant question is, should I stop doing X and start learning Ocaml, or Chinese, or take a welding class because all of that even if it doesn't work out beats scrolling through Instagram.

I don't even take offense with the idea that you engage in activity that makes you money, because pure selfishness on that front would be an improvement to what most people are doing now.