Statistical lifetime of the prestellar phase as a function of density. The green points represent the lifetimes and densities extracted from the right panel of Fig. 8, corresponding to the case of a constant protostellar core mass over time (clump-fed). The blue and red points correspond to the case of a decreasing protostellar core mass over time (core-fed). Tlue points are extracted from the right panel of Fig. 9, while the red points were computed assuming a decreasing protostellar lifetime between 16 M_⊙ and 60 M_⊙, from 300 kyr to 100 kyr. The black dashed lines represent 1,10 and 100 free-fall times.