We have systematically studied quasifission (QF) and fusion–fission (FF) lifetimes for heavy ion fusion reactions which were used in the synthesis of superheavy elements (SHEs) 104 to 118 as well as attempted to synthesise SHEs 119 and 120 using the DNS model. The dependence of QF on energy, angular momentum, entrance channel parameters, deformation parameters and orientation angles are studied. The study reveals that QF lifetimes are larger for the successful reactions than for the unsuccessful reactions. It is also observed that the study of FF lifetimes of both successful and unsuccessful reactions will not give any clue for the reason of failure of experiments to synthesise superheavy elements. It is also observed that the QF process can be controlled by the projectile of lightly deformed or spherical nuclei. The present study finds the importance in selecting the projectile–target combination for the synthesis of SHEs with Z = 119 and 120.