Missing with ball in hand is the ultimate 'take the shot for granted' miss (I'm mentally a couple of balls down the road when that happens). It has happened 2 or 3 times in the last year of intense play. That's just dumb. The misses that are after-the-fact realizations my focus lapsed is what I'm striving to reduce/eliminate.Why do you think you need to practice longer periods of concentration when you admitted that you even miss ball in hand sometimes? Don't you think that maybe the reason is something else? Treat it like a puzzle. Figure out what's triggering you.
Hmm, maybe that's a good clue. I might be a ball or two ahead when I should be focusing on the shot in front of me.
I have a friend (good competition) coming over in a few minutes. We'll play for four hours or so. I'll try to monitor it. The heck of it is, I am completely surprised when it happens. That is, as long as I think about keeping focus things go fine. That's why I was asking about longer periods of concentration. And I don't mean to say I leave the table every time with an 'unexplainable' miss. But it happens enough that I'm asking for advice