Use heavy negatives on the dip machine for triceps. I absolutely love doing these. It's an effective, safe way to overload your triceps with heavy loads.
Have someone help you do the concentric portion of the lift. Then do the eccentric or negative portion by yourself. Take a few seconds to lower the weight.
By definition, a peak is surrounded by two valleys, which means (despite what athletes always like to tell me), you can't be in peak condition all the time.