Simply put if you have a lease agreement you should abide by all the provisions on a regular basis. Many judges are kicking evictions out due to the relaxed way owners decide to do thing when they feel like it.
For example, if you lease says rent is due on the 1st and late on the 5th stick with that. If you allow tenants to start paying on the 10th for a few months without giving them late rent notices and charging late fees you have effectively “Changed your lease by action”.
There’s a reason you have tenants sign a lease. It’s to protect your interest. If you don’t follow your own lease you can expect bad consequences at a later date.