To manage the concurrency, LinkedIn, Bing, and Google all started with manual methods (at LinkedIn, teams would negotiate traffic “ranges” using e-mails; at Bing, it was managed by a program manager, whose office was usually packed with people begging for experimental traffic; while at Google, it started with e-mail and instant messaging negotiation, before moving to a program manager). However, the manual methods do not scale, so all three companies shifted to programmatic assignment over time.
