You can measure anything with VSM. That's not the point.
VSM isn’t about metrics. VSM is about optimizing the delivery of value to the customer. Though VSM looks to metrics to understand how value flows through value streams, simply improving metrics won’t delight your customers. They can only tell you if you’re headed in the right direction. Keeping the goal of VSM in mind - to continually deliver value and delight your customers - will help you focus only on the metrics that will help you make the next step toward becoming a software juggernaut.