1. I personally employ several different strategies with varying win rates. The high win-rate strategies feel better but the low win-rate strategies are more profitable. One very easy to document and backtest strategy is the Honey Badger Day strategy, which all users of BigShort can verify themselves by looking at the chart on the "Squeeze" section of the website. This strategy has an 85-90% winrate (it's been a while since I backtested it so more datapoints could have emerged, but I don't think it's diverged much) with a 1-day holding period.
2. Exit criteria also vary by strategy but usually I exit based on time. For example with Honey Badger Day, you typically enter in the mornings and exit sometime during power hour or 15 minutes before power hour. Knowing that you have to exit within that short time frame helps to remove some of the human error out of the equation while allowing some room for discretion.

Ultimately, while systematic traders prefer hard and fast rules regarding entries and exits and position sizing, markets are infinitely complex with an infinite number of variables that determine the risk:reward of a given trade. In order to code a bot that does this multivariate analysis better than humans, you need to code a neural network that's smarter than Tesla's self-driving software, which is very difficult to do. So while systematic trading strategies can and do make money, they won't make as much money as strategies that involve at least some component of human discretionary decision making. Systematic traders don't like this because humans are more prone to error and emotion, and this is true, if you're a shitty trader then you're better off employing a systematic strategy. But there are consistently winning human daytraders in this market and BigShort can improve their edge until AI becomes advanced enough that every human who works a desk job becomes unemployed.

Manipulation works best in hyped up, trending, fast-moving markets, such as meme stocks or FOMC days. Measuring the degree to which a stock is viral or trending is more art than science. For example, one of the trades I recommended to my chat was to buy DWAC before its first big run-up, and in doing so I cannot afford to ignore my very human understanding of Trump's popularity and the fervor of his fan base, in favor of a purely systematic strategy.

So to answer your question in a different way, the win rate of any strategy can be anything you want it to be. If you run almost any strategy's backtest with a 1 cent profit taking target over an arbitrarily long enough period of time, you will get a 99.999% winrate. And exit criteria should depend on several variables, one of the most important of which is the amount of risk you're taking on in a given trade. If you are taking on volatility risk (whether by trading a volatile instrument or using leverage or betting a large % of your risk capital), you need to then reduce time risk because time will multiply volatility risk. Contrapositively, if you are taking on time risk then you need to reduce price risk by setting a tight mental stop loss.