Estimation, if there is one concept hard to grasp in product development it will be when things are done. With done I don’t mean the releasable increment from the iteration, but rather what will be in it? or in Product Management speak: “what problem does it solve for our customer?”.
I increasingly am practicing randori (sparring matches in judo) and find it has increased my agile fu. It’s a constant adjustment of balance, creating opportunities rather than waiting for them to unfold, follow through fast or the opportunity we created is gone. It’s hard work, time boxed and most of the time I
The key thing in both situations is that we don’t have a lot of time to estimate what will work or not. We can’t plan very far ahead and we have almost no data to make assumptions on, we do know however the extreme boundaries of the assumptions and iterate from there.