We have tens of thousands of lists used in our environment and the only way we can synchronize those lists with our system is to use the GetLists api all. When we do this we have to process every list instead of just those that may have changed in the last X days/months etc. By adding the ability to return only lists with a date created or last modified date in a specified range we could save the processing time both on the Acoustic end and on our end by only returning the relevant lists.