The objective of this work is to address the analysis of photon arrival time distributions (PATDs) obtained using the pulsed optically stimulated luminescence (POSL) technique in two particular situations: (a) when the interval between pulses is insufficient for the full decay of some of the luminescence components, and (b) in the presence of shallow traps. PATDs are important to characterize the luminescence lifetime of synthetic and natural optically stimulated luminescence (OSL) materials used for dosimetry and in luminescence dating, as well as to separate the OSL components from luminescence centers associated with different luminescence lifetimes. In this study we simulated numerically the PATDs that can be obtained in the presence of fast and slow luminescence centers, where “fast”/“slow” is relative to the pulse width and period, and show that the analysis of these PATDs using semi-empirical equations based on a simple model can lead to wrong results when certain conditions are not satisfied (e.g. full decay of luminescence component between pulses, presence of shallow traps). Modifications to the semi-empirical equations are derived to provide better estimates for the luminescence lifetimes in the conditions simulated. Experimental data on Al₂O₃:C OSL dosimeters are used to illustrate the relevance of the results.