I really don't know, hopefully until I retire
Exactly. What I settled on earlier this year is to trade a tiny basket of stocks that have strong moves each day and I got to know them really well, like you know your own kids. I started with AAPL, AMZN, POT and X, and now focus almost exclusively on AAPL and POT. The ability to focus so narrowly makes trading very easy for my ADD self (especially considering I'm also sim trading ES and CL futures every day and posting my CL trades here on ET, no easy task with that mover).
I was hesitant to trade these stocks at first because price appears very jumpy at first. But I practiced in my sim account until I became comfortable, then started trading 100 shares. I now trade 200-400 shares on average, though I had a 1000-share POT trade recently, but wasn't too comfortable trading that size.
This year I traded live on 43 days, and had 4 losing days. No losing day was greater than my average daily profit this year, but my risk management is insane (I use a .15 - .30 cent stop with AAPL as an example).
And on that note:
On 3 occasions over the past several months I traded around 50K shares in a day, one day took 110 trades. They were all my losing days. By the 3rd time this happened to me (and I use the passive tense there because it was indeed as if some trading demon took over my body), I had a long talk with myself and convinced myself that just ONE good move each day on a couple lots of POT or AAPL was all I needed to make a living.