In joint qurbani, where multiple people have shares in one animal, it is necessary to weigh the meat and distribute it accordingly. Distribution should not be done based on rough estimates even if all shareholders agree to divide the meat amongst themselves without weighing it. This is because if the distribution of portions ends up being uneven, it would be considered riba, which is haram in all its forms (consuming, giving, or taking it).
However, if parts other than the meat of the animal, such as the skin, hooves, liver, etc., are also distributed along with the meat, ensuring that each participant's share includes some of these items, then it is not necessary to weigh and distribute the meat precisely. Instead, it is permissible to distribute the meat into roughly equal-sized portions.