How important is it to completely insulate bare wire in outlet?
When using back stabs it is important to use the strip gauge on the back of the outlet. When properly stripped the insulation is slightly supported by the device. If the copper is exposed the wires tend to break at the strip point even if the wire did not get nicked. If the wire was nicked when stripping it can break much sooner without support. With the power off there are usually small slots that another 14 gauge solid wire or a small screwdriver can be used to release the wire trim to the correct length and reinstall.