I find that the hit rate varies depending on what sort of market we are in.
In a bull market, the hit rate on breakouts is much higher than the range you suggest.
In a bear market, the hit rate is can be lower than you suggest, because we will be trading against the trend.
Since we have been in a bear market or at best a sideways market for some time, it is not surprising to me that the success rate from trading breakouts is as low as 40%.
Another aspect is that many of the great traders could make money with a 40 to 50% success rate, because of money management and trade management, which are much more important than stock selection. They will cut the losers quickly and ride the winners, maybe pyramiding them. That way they make much more from the good breakouts than they lose on the bad ones.
However, it will be hard in a bear market, just the same.
I think there are a few filters that can increase the chances of catching good breakouts. These revolve around the two chart models I teach - the value model and the growth model. I explain these in my book Building Wealth in the Stock Market and also in presentations around the country from time to time.
The value model is also explained in the article on the Articles page of my free access web site.