How do you approach creating personas at Eventbrite? Do you have personas that the business-at-large uses versus personas just for launches? How often do you create/refresh the two?

For a full answer, check out my response to the question above about approaching segmentation and personas.

Specifically as it relates to launches, I try to keep of our "business-at-large" target customers in mind (ideally, we've already built product with one of those target customers in mind), but will often double click to understand the sub-segments that would be most interested in what's launching, so that I can further tailor messaging to the audiences that will best achieve the launch's goal. 

For this, focus on the launch's goal is crucial.  Sometimes we launch things that apply horizontally across our base and our goal is to drive broad adoption, so understanding how to message and appeal to each "business at large" segment is important.  Other times, the focus is a lot more specific — either because the product is targeted at a small portion of our base, or because we have intermediate soft-launch type goals.  For those, it helps to go a level deeper.  But in all cases these target audiences should ladder back up to how we think about our business at large.