The Average Trade Profit, Rule 5, of the Money Management Algorithms, is one of my favorite rules. As a daytrader or short term trader, the average trade profit is one of the most important numbers a trader should monitor. Watching thy cycles of a trading system based on the average trade profit can be an effective way to determine when to allocate capital to a trading system.
In general, a negative average trade profit can tell you that a system is under performing, and can be a metric used to "shut off" a trading system. Additionally, a very high average trade profit can signal a very "hot" strategy and could be a time to "stop while ahead".
Using a range that includes a lower and upper threshold for the average trade profit can offer a "sweet spot" trading range for your strategy to trade in its "normal" range.