One of the limitations of using Marketo static lists to create marketing dashboards is that it requires some effort setting up the automation. At the minimum, you need to set up one piece of automation to put leads in the list, and one piece to take them out of the list. Certainly, that's what we've documented and the best way for setting up monthly or quarterly lists.
What about 30 days rolling lists?
I ran into this scenario when setting up a Klip that listened to the performance of a redesigned section on our website. I wanted to compare traffic and lead trends to the previous period (so I could show internal stakeholders that we'd made improvements). The standard way of creating static lists fell short, particularly because I was lining up lead data with a 30 day rolling period from Google Analytics.
Here's how I changed the automation to create two static lists: Leads Current 30 Days, and Leads Previous 30 Days.
Step 1. Set up your triggers as you would normally.
Step 2a. Add lead to Current 30 Day list, set up wait step for 30 days, and remove from Current 30 Day list
Step 2b. Add to Previous 30 Day list, wait 30 Days, and remove from Previous 30 Day list
The beauty of doing things this way is that you don't need to set up additional automation.