Depends on what you mean by a 'standard program'.
Try this:
1-2mo: circuit program, 6-8 compound movements, 30-60s lift (each lift needs to be submax), move immediately to the next exercise. Repeat for desired rotations. Progress goal: increase # of rotations each session.
1-2mo: standard program higher reps, 6-8 compound movements, 10-15 reps, 2-3 sets, 90-120s rest
1-2mo: standard program lower reps, 4-6 compound movements, 4-6 reps, warmup/rampup to 1 max set, 120-150s rest
1mo: maintenance program, during peak competition month, 4-6 compound movements, 4-6 reps, warmup/rampup to 1 submax set at about 75% of previous phase, 120-150s rest
A good circuit program will be highly demanding on the cardiovascular system and improve muscular endurance, much more so than any standard lifting program. So your question should be WHEN do I need this? Your answer should be following a time of down training or when coming off injury when your body will respond to circuit training the best. At the opposite end, doing circuit training while in the middle of a highly intense in-season training program is like pissing in a swimming pool...the pool is already full. You COULD, if you desire, use circuit training as a means of cross-training IF you have a true cross-training day. Example: Thursday: swim + circuit training.
Alan