ad-hoc is bad
	didn't take time to design the system
	end up with architectural flaw
	waste time doing things customer doesn't want
	no clear marks, milestones; hard to track progress
	doesn't work very well for multiple developers, new coders
	when are we done?
	
drawbacks of waterfall
	if software impl. doesn't satisfy users/customer, wasted lot of time
	nothing to show until end
	difficult to implement, have to go back to the drawing board
	not easy to parallelize
	lots of time "wasted" up front
	you may not know all the reqs./design at the start

evolutionary
	have something to show earlier
	responds well to changes

-
	when are we done?