How do leading alcoholic brands use E-bidding for media planning and buying?

I would like to understand how much of the media spend is put on bidding (all of the media spend, part of media spend or none of it) by leading alcohol beverages companies like Heineken, Ab Inbev, Carlsburg etc.. Also, which platform are majorly being used for E-bidding? and what is the type of saving that these companies receive out of it as compared to traditional media planning and buying methods?