One of my most memorable conversations during training went something like this…

Student: Aren’t these just best practices? I don’t see how this is agile estimation. How is this agile?
Me: Hmmm. I guess they are best practices. I see many agile teams frequently apply all these techniques when they do some estimation. Let me ask you about your current project. Do you get people who will do the work to give you estimates?
Student: No. Either we have a group of architects to estimate the work, or I estimate the effort for the team.
Me: Do you try to make make sure more than two people estimate?
Student: No. One person should be good enough to estimate.
Me: Do you try to understand or uncover the assumptions that person is making during estimation?
Student: Sure. We ask them to write their assumptions down.
Me: Do you use relative estimation?
Student: No.
Me: So you’re telling me that even though these are best practices, you’re not necessarily doing any of them?
Student: Yes. But I don’t see how this is agile.

When people get fixated with disagreeing about something, they stop listening and stop learning. Drawing them out of this corner can be a really difficult task. In this particular case, the student wanted clear evidence that agile was something else and wasn’t prepared to hear about estimation best practices being normal best practices when working in a most agile methodologies.