I find it challenging to estimate my own time in tasks. Part of every task is figuring out how to actually do the thing you are wanting to do, and sometimes that takes 5 minutes and sometimes much longer. So I am terrible at estimating my own time, and even worse at estimating someone else’s. It doesn’t add pressure to a person if you give them a time goal they know is basically arbitrary.
This is what scrum (done well) helps with. Unless the software was horribly written, it’s usually easy to estimate effort for very modest, well-defined changes.
Take a large enhancement or overhaul, however, and estimates will be wildly off and it’s because of the iceberg effect of unknowns.
What scrum forces the inexperienced teams to do is start breaking down, plan and incrementally chip away at a ill-defined, large request by turning it into many smaller and better understood deliverables.
It’s what very good teams do, though they do it without the need for formality.
