To further illustrate the workflow of photon flux determination through radiometry and ray-tracing, we applied the same course of action to two distinct intensified reactor systems. The first system is a wellestablished microcapillary flow reactor, one of the common lab-scale reactor types that have seen wide applicability due to their operational simplicity, low-cost fabrication, and ease of assembly. The second is the high-shear spinning disk reactor, specifically the photo rotor-stator spinning disk reactor (pRS-SDR), a design pioneered by our team. Unlike the non-intensified batch reactor, these intensified reactors function in a continuous-flow mode, presenting the potential for scaling up photochemistry. Importantly, the two selected intensified systems vary considerably in their operation, reactor geometry, light source, scale, and reactor-light source configuration, showcasing the versatility of our workflow (for an overview of the workflows, see Figure and).