How do you get engineers to share data for marketing case studies?

Every time we try to write a case study, the biggest bottleneck is actually interviewing the internal team.

Engineers are busy fixing bugs, PMs are on to the next launch, and nobody remembers the exact metrics from months ago.

It feels like 80% of the effort goes into back-and-forth calls just trying to rebuild what actually happened before writing a single word.

How does your team capture project details early so you don't have to chase people down later?