Ever heard about man-days? If not - good for you! But if you are like me and had a dubious pleasure working with it, I feel your pain.
Man-days are just a way to determine how much time will take the development of a specific feature. Yes, you read it right. It's a different way of estimation. I don't like estimates at all, but that's not today's topic.
So, what's wrong with estimating in man-days? First of all, it's a clear indication that your team doesn't care much about quality. They focus on delivering. And it's ok when it also brings value for the customer. Sadly, this way of running a project doesn't leave much space for quality nor customer value.
Why is that? Because you, as a developer, are accounted for finishing your task at a specific time. After you are done with one thing, you start another. And this is how the vicious circle starts.
You want to look good and fit the time frame man-days are imposing on you. You don't have an opportunity to refine your work. You make one thing work and jump on another, trying to do it on time. And you start to rush things. That's where we lost quality.
Another aspect is that someone has to develop that specific number of days in which the feature had to be done. You sit around a table, do some analysis, and throw numbers. The more experienced developer said 3 days. You think it will take you at least 4 days, probably more. And then you all agree on 3,5. Seems fair, right? But what if your analysis was wrong? What if you missed some cases essential for the customer? Will there be any place later in the development process when you can fix it? Of course, there won't be any. The scope of the feature and needed time was just carved in the stone. This is where product value is lost.
Now our circle has closed. You make assumptions during the analysis that can and very often will go wrong. Based on these assumptions, you rush things to do it on time. And you leave no space for refining work or having second thoughts about the feature. Welcome to the feature factory with a hint of waterfall flavor.