In my 12 year career I've worked in a variety of development roles and seen periods of extreme growth and periods of stagnation. The periods of growth are highly rewarding and exciting. They are periods where all you see is opportunity for innovation and you just want to build and build and build. The periods of stagnation are quite the opposite, you get bored, your solutions become less innovative and you risk burnout. Not to mention your career goes nowhere if you remain in a permanent state of stagnation.