[szaroubi]

Getting a PR or marketing campaign up must be done in parallel to the dev work. It can take a few months to find the right journalists in the right publications , get their attention and get their time. On another note, some product launches are also times with fixed date events (Back to school (media industry), CES (Consumer electronics), any other expo in any other industry). it is key to time the dev deliverables. and if you need to chose between two features to dev, well, you need estimates as in inputs.

Estimates are not perfect, you should not spend 5 man days to plan 2 months of work. Planning can be done with guestimates and best effort and when done right, are super useful.