Before my current set up I went through a few kit zooms and basic primes.
I currently own six lenses and bought them in this order:
17-40mm f4L (July 2007)
24-70mm f2.8L (June 2008)
70-200mm f2.8L (Nov 2009-before this I had an old 80-200mm f2.8L since 2006)
50mm f1.2L (Jul 2010)
100mm f2.8L HIS (Jan 2011)
Sigma 85mm f1.4 (Dec 2011)
Thinking about it, I went trough the zooms first to cover all the bases I really needed, then got primes to address specific needs, mostly for portraits and product shots where I wanted greater DOF. I'm in no rush to buy any more lenses soon, but when I do it'll be more primes as I do prefer the IQ.
I was wondering if other people went through buying phases like this or do something more mixed? No specific reasons for asking, just chilling out on a Monday evening when I don't have much to do work wise