[jusuchin]

> Say what you want about our supposed inability to estimate, but I challenge any team to nail estimates within a 20% margin for a large feature on a large app.

Not to be pessimistic but this sounds like stories and tasks needed to be broken out in even finer detail.

[digitalclubb]

I think that's a fair assessment. If people can grasp creating small independent deliverables for their projects (of any size) then things become a lot easier to estimate. Monitor velocity and pull less into future sprints if you're still getting it wrong.

If there is a piece of functionality that brings unfamiliarity to the delivery team then create a spike ticket to investigate (though use them sparingly).

If you break things down small enough, really understand your velocity and have a transparent relationship with your product owner then there should be no need for any stress from anyone.