Technically the ritual is more of a sith tradition (which Osha is not) and vader's long battle was specifically unique to him, it was meant to show that he had internal turmoil, hence why Dagan Gera, while not fully bleeding his crystal, leaving it an orange colour, did it much faster.

I think we can also understand the speed at which she did hers was because it could represent her rage in the moment, anger is usually spontaneous and then calms, along with the direct with the crystal I think that could explain why it was so fast, she had this burst of rage.