In this letter we prove explicitly that if Hartman effect exists for an arbitrary 'unit cell' potential, then it also exist for a periodic system constructed using the same 'unit cell' potential repeatedly. We further show that if Hartman effect exists, the tunneling time in the limiting case of a sufficiently thick 'unit cell' potential is same as that of its periodic system. This is true for any arbitrary value of the intervening gap between the consecutive 'unit cell' of the periodic system. Thus generalized Hartman effect always occurs for a general potential constructed using multiple copies of single potential which shows Hartman effect.