You do need to be attentive while using cc at all times. It's no substitute for driving.
When I was going extremely fast with the cc activated (that one time) on a rain slicked road, I had my foot hovering over the brake in case I needed to disengage it quickly. And it helped that the road was straight as a ruler for miles and miles....I was too scared to worry about hydroplaning..I just wanted to get out of the darn storm!
(plus, there were people going much faster than me. One Crown Vic heading the other way must have been going 120 or so....)

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