2019 Optical Society of America. We report on the action of exposure time and peak Intensity on the growth of long-scale focal volumes in multiphoton polymerization. Using modified engineered Bessel beams, we explore the effects that rise during the voxel growth, while we present a counterintuitive action of the expected expansion of the polymerized volumes that is revealed for a specific range of peak Intensities. We show that there is a regime where the higher exposure time (number of pulses) creates shorter polymerized strings in comparison to a lower number of pulses, and we determine the polymerization thresholds.