I thought to share a comment I posted to very interesting blog post by @dennisstevens.
I asked few question from Dennis in twitter already but then I thought sharing and elaborating them here.
I am a co-founder & CTO in a startup that practices continuous flow in product development, though we used to practice time-boxed iterations. If you care to read how we changed our process just take a look at: http://huitale.blogspot.com/2009/10/huitale-way-is-it-scrum-or-is-it-kanban.html
And our current way with total value stream: http://huitale.blogspot.com/2010/03/huitale-way-our-value-stream-map.html
In twitter I challenged the point "Continuous flow makes most sense when the outcome is pretty clear and feedback is not as likely to impact subsequent work". For us it has been the opposite. It made sense to drop time-boxes to enhance the feedback cycle (one piece flow, faster cycle time, faster feedback from the market).
Eric Ries has defined A startup as "a human institution designed to deliver a product or service in conditions of extreme uncertainty" so it is has nothing to do with the size of the company, the sector of the economy or the industry the business is involved in. For me it means two things in this context: 1) there is no stable product 2) feedback from your internal iterations is less valuable than iterations that you do together with the customer (customer development is the thing that we talk in lean startups). Therefore getting stuff out faster (continuous flow instead waiting for the time-box to end) gets you the feedback faster.
Under these circumstances we practice continuous flow and it seems that our findings seem to contradict the claim that "time-boxed iterations work best at the outset with a new product, new technology, or substantially new set of features.". If I would have written similar blog entry, I would have told the opposite and that made me wondering is it just me :o)
I also happen to consult companies with agile & lean and usually help them start with iterative time-boxes. Why? Because time-box gives a boundary in their chaotic environment. Starting with continuous flow would be too hard as they do not know their WIP nor their value stream(s) and figuring out those will take some time.
So my conclusion would be:
Iterative time-boxed approach makes most sense when you have chaos and you need to establish a boundary to get something done.
Otherwise prefer continous flow.