Can you terminate a tenant for being late 18 times out of 32 months?

I guess you could, if it's written in your rental agreement.  Why would you?  I have a tenant that has been doing this for years, is always "locked out", we have raised his rental rate numerous times and get an extra 15% above that.  He is not using our gate (no wear and tear) as he always is locked out.  Technically I make more off his unit than the ones paying on time. 

I would suggest, instead of giving her a 30-day notice to vacate, give her a 30-day notice you are increasing her rent (15% or the max allowed in your state).  Make the hassle worth it!

Is your rent due on the 1st? We won't accept partial payments for anything less than what's due on the screen, so if they want to pay for last month's rent, and this month's rent is also due, we say no, come back when you have all of it. Works OK for me, they just get wise and make the payment on day 29 sometimes. Then they get locked out and have a late fee 11 days later, I don't mind, it's good money, I do hate the work involved and the monotony of the same thing happening over and over, but as Anita has pointed out, we're making more money from these repeat offenders. If you're in CA you can apply a hefty 1st late fee according to your state law.