The way I work, I spend several days or weeks thinking, drawing diagrams about the main concepts and architecture, but when it's time to implement, I like to get the project done as quickly as possible. I don't usually encounter unexpected problems on projects; that's what the planning is for.
If you've figured out the right architecture ahead of time and you've solved all the obvious technical hurdles in your mind ahead of time, then implementation is very straight forward and yes iteration time makes a huge difference.
If you've figured out the right architecture ahead of time and you've solved all the obvious technical hurdles in your mind ahead of time, then implementation is very straight forward and yes iteration time makes a huge difference.