I have worked on a lot of online campaigns, majority of the times the campaign is launched, and then the analytics team typically starts reporting on the KPIs (Key performance indicators) on a weekly or bi-weekly or monthly level.
The key question is what does the strategy or the marketing team does after getting the results. The marketing team should look at the reports carefully at the most granular level (placement or creative) for display campaign and then start optimizing based on the results. Sometimes combination of metrics needs to be taken into account for example the cost, engagement rate, interaction rate, conversion rate etc.
It is very important that the optimization takes place sooner rather than later. The optimization process should be establish and then followed week over week. I have seen that this is very important for campaigns whose key success metrics are ROAS or ROI. As the campaign manager is trying to generate highest revenue for each dollar spent.
If the campaign’s purpose is to increase the branding/engagement then it is important that the placements driving higher Click-through or Interaction rate should be served higher impressions. The relevant publishing sites should be used. The capability of Ad networks like Ad.com, Specific Media, and Context Web should be fully utilized to get lower priced media and target the relevant consumer targets.
Some portals like Yahoo! are also able to use Behavioral Targeted placements to better target the consumers to help increase the brand awareness and also increase the conversion rates.
The key is to start optimizing sooner rather than later..