The motion sensor itself doesn’t actually do anything to control the lights. All it does is send its “motion detected” Report (checking on the interval you have it configured for) and then it sends its “inactivity detected” report based again on an interval you have configured it for.
You will then set up various rules in SmartThings for handling those two reports. This is what allows you to have different rules for different times of day or whatever.
So you can pretty much make the rule however you want it to be. Particularly if you use core. You could have it do any of the examples you gave in your post, it’s just up to you what will work better for you.
If you want to have a timer that keeps resetting, you could have that.
If you don’t want to have the timer reset, you could create a rule that is just based on the first Report of motion.
Many people use core to create a manual override so that ordinarily the system will turn the light off after a specific period of inactivity on the motion sensor, but if someone hits the manual switch on the wall, then the light will stay on until that switch is turned off.
Pretty much anyway that you can conceive it you can write a rule using core to implement that logic.
If you want to verify any specific concept, just ask in the core peer Assistance thread and the core experts there will be glad to tell you if it is possible.
But one of the best things about SmartThings is that you don’t actually define the logic in terms of the device. The hub collects the reports from the devices, but then you manage the logic in the rules (in the case of core, a rule is called a “piston”)
For example, there is a motion sensor in the bedroom at my house. During the day, if the motion sensor sends an activity report, the system ignores it. Nothing happens.
In the evening, if the motion sensor sends an activity report, the system turns on the overhead light in that room.
Then at night, when I am ready to go to bed, I change the “mode” on the system to “asleep.” Once the system mode is “asleep”, if the motion sensor sends an activity report, the system does not turn on the overhead light in that room. Instead, it turns on a soft night light on the wall.
Every morning at 7 AM, the system mode is automatically changed back to “daytime” and then the motion sensor activity reports will be ignored again.
So you see, the behavior is not tied to the specific motion sensor device. Instead, I have created rules in the system which determine how the motion sensor report will be handled when they come in based on other context. 