i've played it a few more times and my error is regularly under 4 now, in less than 170s
but i think this really has more to do with training as an artist than doing math. there's a famous story about an artist ((can't remember who tho)) who was to be commissioned by a king to do some work. he was brought before the king and asked to demonstrate his credentials, to prove he was an artist -- so he asked for something to draw with, and free-handed a circle. it was apparently a pretty accurate circle, and the king was satisfied & gave him the commission.
“That’s your drawing?” asked the courtier, who didn’t know whether Giotto was pulling his leg. “Is that all you’re going to send His Holiness?”
“That’s more than enough,” said Giotto. “Send it with your other drawings and see whether it’s understood or not.”
The Pope’s messenger took the drawing and went away trying to hold his temper. Did that little painter think he was a fool?
When he got back to Rome he showed the Pope the big O and told him how Giotto had scribed it—freehand, without a compass. The pope and his advisors DID understand the achievement of that O and gave Giotto the commission