When is the right time to raise rent?

[Franky Juwana]

hi all, 

     I'm just curious, for all landlords out there, how do you manage your rentals? do you raise rent? why or why not? Friend of mine who has been a landlord for over 15 yrs suggested if the tenant is good, do not raise rent, maybe after 4 years, if you want to get rid of them, then raise it.  

What do you guys think?