Short feedback loops are one of the key benefits to the success of agile because they enable teams to learn fast and adjust. This technique is leveraged in numerous practices used by agile teams including the daily standup, sprint demos, code checkin, build and validation cycles, pair programming, and continuous delivery. One of the key benefits that convinced me to try agile was its claim to deliver greater value with higher quality. After I had experimented with agile for a while, I started to understand just how critical short feedback loops are to achieve these goals.
Short feedback loops enable you to learn fast so that you can adjust while the costs are low. It has been well understood in software development that the cost to fix a defect increases and in many cases increases dramatically the longer you wait to fix it. Some of the reasons are that more code may have been added making the defect more complex to fix, the new code requires additional testing and fixing, and by the time you get to the fix, you may have lost familiarity with the code in question. To combat this issue, it is critical to find defects soon after the code is checked in. One short feedback loop used to combat this is to automatically test the code through a series of progressive test gates. Additionally if the code is checked in frequently (another short feedback loop) developers get quick feedback on quality.
Another manifestation of short feedback loops is the daily standup which enables teams to identify critical blockers and get help to get them fixed before the next meeting. Someone has a problem, someone jumps into help fix it. Shorten the time to fix a problem; reduce the cost.
To ensure that agile teams are meeting the needs of their customers, they demo their new work at the end of each sprint to get timely feedback. This version of a short feedback loop is fairly well known to agile teams but it may be surprising how few teams actually do these with their end users. These demos give the product users ongoing updates on how the new code is progressing and the opportunity to provide feedback. This kind of feedback is like bug fixing, the sooner it is applied the more cost effective it is. Going a step further, releasing functionality frequently enables users to get traction and provide feedback before the functionality is complete. Customers have to be willing to experiment and respond but the win for them is that they do get an active voice in getting the value they require.
As teams continue their agile adoption, it is useful to remember why we adopt various techniques to make sure that we get the value promised. To deliver higher value with better quality we use short feedback loops so that we learn fast and adjust.