I disagree that the exit is completely unimportant. If it's not important where will you place the stop, or you say you don't need a stop?
What is a high probability entry?
Maybe I got it wrong, but will you enter a trade and whenever you will decide to close it, it will be OK?
I my opinion saying high probability trading is more correct than saying high probability entry. It can be a high probability setup relatively to the exit.
When I tested my method I saw that if I was scalping only 10 ticks I was getting about 75% of winning trades.(In my opinion this is high probability trading) If I was scalping more ticks I was getting a lower percentage of winning trades.
When I tried a trailing stop, I got a even a lower percentage of the winning trades, while the profits increased. (The total profit increased, but with bigger draw downs).
So the idea is that based on the exit, "the probability of the setup" changes.