During biomass growth, trees sequester biogenic carbon. The carbon dioxide absorbed from the atmosphere can then be stored as carbon in wood products, which is eventually released at the end of the product’s lifetime. Although temporary, this carbon storage can contribute to global warming mitigation and is increasingly considered through dynamic Life Cycle Assessment (dLCA) studies, which extend on conventional LCA by dynamically characterizing the timing of emissions. Doing so, current dLCA studies often employ a regrowth approach, where biogenic carbon sequestration is modelled gradually as the tree grows, based on a method using biomass’s technical Rotation Period (tRP) as a case-specific time frame during which the harvested biomass is expected to fully regrow. Because dLCA time-weights emissions, shorter tRPs typically result in lower dynamically characterized biogenic carbon emissions, thereby incentivizing short Rotation Periods. However, tRP generally reflects forestry management objectives rather than inherent biological growth dynamics of the biomass. Therefore, this study assesses whether using tRP is a valid approximation for modelling the regrowth timeframe in dLCA. By comparing dynamically characterized biogenic carbon emissions of Norway Spruce (picea abies) harvested after 60 years and used for plywood (i), Norway Spruce harvested after 100 years and used for beams (ii), and Scots Pine (Pinus sylvestris) harvested after 100 years and used for beams (iii), this research exemplifies that by equating a short harvest timing to a high carbon sequestration rate, the use of tRP can lead to an overestimation of the benefits of short technical Rotation Periods. To conclude, using tRP as a proxy for regrowth time can misrepresent actual carbon sequestration dynamics and overstate the global warming mitigation potential of short-rotation biomass products. Therefore, more biologically grounded modelling approaches are needed to accurately assess biogenic carbon in dLCA.