We a lot of the time do intervals in Crossfit. These are workouts where you have a set amount of time that you determine the work and a set amount of rest. Another general kind of programmed workout are ones for time. But when you look at most "for time" workouts, they really are extravagant intervals, where you go back and forth from work to rest in all kinds of crazy ratios. Here is a photo of Matt and Erick from West Marine in that very ratio.
5 Rounds - Running Clock - EMOM:
1st minute: Prowler Push 30 meters (180/270#)
2nd minute: 15 Toe To Bar
3rd minute: 15 Hang Power Snatch (55/75#)
*perform the given movement and reps within the minute