When planning work ahead in your sprints avoid guesstimating at all costs
Why? By guessing estimates for weeks of work ahead you're putting yourself and your team in a corner: when unplanned things show up (and they always will) there is no turning back as you've already committed to delivering per your sprint
Optimists are guesstimating for less work than there actually is which causes the need for Overtime, low quality deliverables, messed up roadmap schedule, and feeling of failure at the end
Pessimists are guesstimating for unrealistic and unjustified work which is even worse than being an optimist - this raises a red flag that a team isn't capable of doing good work in realistic time
Unfortunately even when a team is capable of finishing work in good time, by being a pessimist from the start the original estimates become self-fulfilling prophecy and the work expands to fill out all of the allocated time
Realists on the other hand are different from optimists and pessimists simply in being good JIT planners and proactive communicators
How to recognize an optimist or a pessimist?
a) Sprint contains many part1..part_n type of tasks in the sprint
b) Multiple different tasks have identical estimates of n hours (usually equal to max. daily deliverable limit)
c) There are no internal testing or peer-review tasks, only work specific tasks
How to become a realist?
1) As a ScrumMaster dedicate a few hours time to meet with your team when planning a new sprint and take input from all team members when estimating task hours.
One-man 15min sprint planning is a recipe for failure
2) When encountering goals that require more detailed research before the work can be broken down into clear daily deliverables, plan for a spike-goal of a few hours that will result in more detailed planning of the work ahead.
This is JIT planning by utilizing Spike goals and it helps to avoid doing complex planning for weeks ahead
3) Unknowns still show up even to the best of planners - when this happens figure out what happened, try to devise the best plan for solving the new situation, and if you see the original estimates are no longer viable make sure to immediately inform all stakeholders
