Board Thread:Episode Discussions/@comment-1181222-20170830100203/@comment-5085906-20170903065101

@Kakashisologod1

Only when they are experiencing a surge of emotions. Even then, without establishing a good relation with the Tailed Beast, they cause more damage to themselves in the long run because their life-span is shortened with each use of V1 or V2 chakra cloaks, not to mention being exposed to the risk of having the Tailed Beast take over.

The Sharingan does not discriminate the person in which it awakens - they only need to experience emotional trauma and voila! Sharingan awakened. And even if they can't upgrade it to three-tomoe, they can immediately skip to MS if they experience loss. Where as in most Jinchuuriki cases, the person who becomes a Jinchuuriki needs to be a skilled, level-headed ninja first before becoming a jinchuuriki. Of course, that was not the case with Naruto and Gaara, but still..