In assessing highly photon transmitting systems, understanding the effective optical path length is essential. However, as a preliminary step in our proposed method, we sought to underscore its limited significance in a photon-efficient context. Our initial experiments, therefore, targeted a basic setup anticipated to have a sufficiently long effective optical path length. Hereto, we employed a batch configuration, which consisted of a test tube (13 mm inner diameter, 15 mm outer diameter) filled with the reaction mixture and illuminated by a high-powered LED light source. This off-the-shelf lamp offers four distinct power settings, enabling us to evaluate the same batch setup across four separate data sets. Instead of the conventional chemical actinometry approach to assess the photon flux absorbed by the reaction mixture, we used a combination of radiometric measurements, 3D modeling, and ray-tracing simulations. Fundamentally, our methodology zeroes in on an exhaustive characterization of the light source, harnessing this data to fine-tune a corresponding model, and subsequently applying this model to a virtual rendition of the experimental setup.