Increasingly higher doesn't mean impossible though. If your field isn't scattered and you're busting lines every deal you can keep going. As soon as you mess up a couple times they'll screw you. The strategy does change once you've reached your high score. I think careful placement beats line-every-time at that point.

I find taking a break to be better mentally, because you've been working towards a goal and get there and then I get rammy and overconfident. 20 minute sessions max.