If you have a lot of big user stories, your velocity will jump up and down wildly. This makes it extremely difficult to tell when a user story will be done. Breaking down your huge user stories into smaller ones will help you smooth the flow and give you a clearer picture.
For a team new to agile software development, estimating user stories is not easy. The team is used to estimate tasks in hours and days, and know they’re never right anyways. So why bother? In agile, estimating user stories relative to each other using story points can give you a fact based idea about what will be done by when. But how can you do it?