By irrational case I mean here asking the team for an opinion about an irrational amount of work or considering an irrational amount of time to complete some work. Here are the examples:

A Scrum Team is planning to execute some manual regression tests that they know cannot be completed in one sprint. They want to spread the execution through a few next sprints. The Product Owner wants to get agreement with the Development Team on how much of the regression can be completed in the current sprint. The regression has already been divided into well defined, small or medium backlog items.

The Development Team stucks in the discussion and they find it difficult to discuss how much of the regression they can do. The Scrum Master may ask questions like these:

- (A) can you do exactly one regression backlog item in this sprint?
- (B) can you do half of the regression in this sprint?

Question B is targeted at establishing a limit: is there an amount of regression that we think is maximum we can take into this sprint. Even at the expense of not doing any functional stories, or very little functional stories. In order to establish this maximum amount, we can start from an amount that we know is not realistic, like half of regression.

Another example is the ability of a Development Team to work concurrently on a story. Sometimes it is a challenge for a team to have multiple developers working on a single story. The Scrum Master wants to guide the Development Team to establish how many developers can possibly work on that story to help them understand the possible shortest duration of work. So, similarly, the questions could be:

- can this story be worked on by one developer? Certainly yes, but if so, can we have two? Or three?
- can this story be worked on by 9 developers? It is not likely that this happens in real life, so they are likely to say "no". But then maybe 6 or 7 is good?

- can this epic be developed in, say two sprints? we know the team will say "no", but let's continue the discussion - maybe four sprints is enough?
- assuming this epic is really tough and most of things that may go wrong actually go wrong - can this work extend beyond 9 months? No... that's unprecedented. Not even with the hardest and biggest epics we remember did it happen. OK, so then we know at least that it is going to take less than that. How about 6 months?