In the context of media buying vs media planning, how does your organization balance strategic decision-making and execution for optimal results?

In our organization, given a huge service line, we determine the key priority areas where we will be putting the media budget other than branding. Once that is decided we go back to media planning, and decide which media houses, online campaigns, ads we will spend on, based on the focus - demand gen vs. awareness. Post this, media buying starts based on COAs, ROIs, Reach etc. 

Media planning has been decided on the available inventory and required communication mediums for the target segment. Media buying is further streamlined to justify the budget spends while taking care of the objective of the campaign in terms of brand awareness, Customer service or acquisition led campaigns. Media buying is further tuned as per the needs and requires outcomes while taking care of available budgets.