Gary Milner discusses the importance of managing the digital marketing supply chain. He notes that inefficient media management can destroy brand impact and waste up to 80% of spend. Milner advocates reducing the number of demand-side platforms (DSPs) used and curating supply through select SSP and private marketplace partners to gain transparency and reduce costs. He also warns against using audience extension without the permission of premium suppliers. Milner predicts continued shifts from open to private marketplaces and the growth of programmatic creative powered by artificial intelligence.