Time boxing is the technique used to control and plan iterations. A fixed amount of time is allocated for each component at each stage of development. You can compare it with an eight o'clock news bulletin. The news must start at eight o'clock no matter what happens.
Time boxing can only be performed using a tool that generates the basic functions. USoft Developer supports the concept of time boxing very well because at any moment in time you have a working application and you are always guaranteed to have the basic functions working.