No this is not a post about music. It's about software development and more importantly delivery.
Before I progress we are all agreed that we are mammals, therefore have an inbuilt rhythm - http://en.wikipedia.org/wiki/Circadian_rhythm - this is usually a 24/25 hour period in which we all sleep, wake, eat and go to work or do something else!
So let's elaborate further and take this in to the realm of software delivery. It appears that we (mammals) need rhythm - "Although circadian rhythms are endogenous ("built-in", self-sustained), they are adjusted (en-trained) to the local environment by external cues called zeitgebers, commonly the most important of which is daylight.".
This is where software delivery comes in, I'd like to take SCRUM as the example of setting up this rhythm. Every 2 weeks we'll deliver software, have some planning and retrospect. This sets the pace for the delivery - team members know when things are happening and therefore can get in to a rhythm. The team understands when the start and end is - they have a focus too for a given time period.
Now I'm an advocate of delivering more often (every couple of days), but I believe that until you can do these things well which is walking, you can't sprint (no pun intended).
The other rhythm is that of the daily stand up - this occurs at the same place & time each day.
Other Agile practices seem to promote the same ideas - such as the TDD cycle, pair programming (if you pair well - i.e. swapping the keyboard!!).
It appears that with no rhythm you'll deliver software, but maybe you won't be going as quickly as you can.