I Airpolice, you say... I'm also curious about the need for a much larger circuit, just because the speed is higher.
It's all about scale and time available, a slow Piper Cub can quite easily fit a circuit inside almost every other aircraft, and would never require more than a one mile Final. An Airbus or Boeing will always aim to have a six to ten mile final, they are often asked to control their speed to a standard 160 knots to 4 miles. The Cirrus just sits somewhere between these two extremes.
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