I'm wrapping up my week here in Chicago, and it snowed yesterday. Cabs were scarce. I walked. Many others walked too, about half with umbrellas to protect themselves against the snowflakes.
Most systems are designed to handle typical average conditions. Taxi cabs in a city, for example, handle typicalamounts of traffic.
IT is different. In many cases, IT infrastructures are designed for the peaks, not the averages. Peaks can be where you need performance the most, and failure to design for peaks can be disastrous. As with any business decision, this represents a trade-off. Design for the average, and suffer through the peaks, or design for the peak, and be over-allocated and under-utilized most of the time otherwise.
The choice is yours.