
Each team building another component has been using the most recent tested
version of the integrated system as a test bed for debugging its piece.  Their
work will be set back by having that test bed change under them.  Of course it
must.  But the changes need to be quantized.  Then each user has periods of
productive stability, interrupted by bursts of test-bed change.  This seems
to be much less disruptive than a constant rippling and trembling.
- Frederick Brooks Jr., "The Mythical Man Month" 
