Absolutely. The majority of the venues only have one circuit. They may have multiple outlets, but they are commonly on one circuit.
Newer venues do better, but the average venue in these parts is better than 30 years old.
Wow, thats interesting because I've NEVER been to a venue with only one circuit. Even the pool pavillion I play in alot has more than one I can access. I'd be very suprised if an entire venue only has 1 circuit.
At a school winter formal last weekend we used 6 circuits and that was a stretch, with that particular show, 8 is more in the comfort zone.