+100,

It's nearly impossible to crush or otherwise damage a carbon bar by over tightening. The bolt or ears are likely to crack off long before that.

The culprit is poor fit, and that's been mostly resolved as tolerances were tightened to accommodate the needs of CF parts. Much of the mythology and paranoia about CF post or bar breakage dates back to the beginning of the CF era. CF posts were used in steel frames without consideration of the difference between how a CF post would clamp vs the alloy post it replaced.

When two non matching (almost) round parts are clamped one must distort to match the other (or both distorting part way). With an aluminum post in a steel frame the thin steel seat tube took the shape of the stiffer post, and there wasn't a problem. But when a carbon post was put in that same frame, it's thinner wall was ovalized by the stronger steel tube, and began to crack or split lengthwise, compromising much of it's strength. Also the ear design of many frames or clamps caused the ears to dig into the back of the post, in a way similar to putting you thumb into an egg when holding it too tight.

So there was a learning curve, but today's, slightly stiffer posts, combined with good roundness and tolerance in frames, and better clamp design have basically resolved the problem. Still it pays, not to be too ham-fisted because it's fairly easy to break a bole or the clamp's ears.

The best solution is to use a traction compound so you can get reliable clamping hold at lower clamping force.