=====8<---------- Start of note-to-self 002, Keep Records! Measurement & calculation beats guesswork ----
Sometimes I have to reminded myself to "eat my own dogfood" (or "take my own prescriptions")
Why should I not apply the same principles to facilitation that I recommend for software development?
Yesterday's Weather is perfectly applicable to meeting facilitation - if you know your tasks.
It's rather a high probability that the same task with the same amount of people in a retrospective (e.g. gathering data via a FrIm Chart) will take more or less the same amount of time.
So - to develop a plausible agenda - it's helpful to record the time each task took and the relevant circumstances (Time of day, number of participants etc.)
Therefore: Keep Records!
In the case of retrospectives you get a very sound foundation base your planning on data instead of guesswork very quickly. I'd say 3 Iterations should gauge your instruments [for that team] pretty precisely.
=====8<---------- Start of note-to-self 002, Keep Records! Measurement & Calculation beats guesswork ----