If you’ve made many banner ads before then at some point you’ll have had a situation where the client dumps a whole bunch of specification docs, from various publishers and ad systems and perhaps a complex excel matrix outlining the launch dates, variations and limitations and expect you to take on the task of collating it all into a list of deliverables. In short, a mess.
This one is a bit like a hot potato with everyone trying to avoid being responsible for making the call on the definitive list of requirements for the final files. Ideally this should be collated and presented as part of the brief/scope however banner builds rarely run like clockwork.

This why Ad Developer was formed, a one stop shop to sort out the process for you and deliver an end to end service seamlessly.