Hey Janna, there are many techniques housed within foam rolling, each creating a slightly different effect. Compression is one that can help improve fluid dynamics and neural sensitivity. Adding Vibration causes micro-contractions to occur local to the Vibration which enhances fluid dynamics in a more passive manner (let the vibration do all of the work, no need to roll up and down!).
If using a Vibrating Roller, I’m a fan of spending 1-2 minutes on a muscle, adjusting where the roller is placed in a certain area every 20-30s. For example I might spend 30s each on the Achilles, the medial Belly of the gastroc, the lateral Belly, and behind the knee where the gastroc and hamstrings intersect. If I’m time starved, I might just pick my most problematic area.