A lot of the setups I trade that use time targets are larry williams type stuff where you enter with the expectation that you are trying to capture wide range days. Because WRD's often open near the low (high) and close near the high (low), I will sometimes utilize a wide trailing stop with the optimal exit near the close utilizing a time stop rather than a profit target/exit. Most of those setups are based on patterns for possible reverals or narrow range breakouts, etc. I trade some breakouts with the expectation of exiting on the close the 3rd day, but it depends on the market. In general the axiom, it takes time for profits to grow is recogonized by many but utilized by few. Now with losing positions. I got no time for those. Exit as soon as you know your wrong.
...when I develop a mechanical system that works reasonably well in a broad time frame (which for me is an hour) the very last thing I do is to backtest stop times and "too late to enter a trade" times. This often has a dramatic effect on the performance of a system which was profitable without them, not only making the overall profitability better, but also improving the slope/sigma of the equity curve.