Pretty much anything that works for one light can be made to work for multiples if only by having one light follow the other. The first question, though is really what behavior you would like to see.
Lighting Controls are Based on Lifestyle and Personal Preference
Lighting is one of those things that’s very personal. Some people are fanatics about saving energy and they will set the lights to turn off after 15 minutes no matter what.
Some have fairly regular habits, and will set the light to turn off after 10 minutes of inactivity. This will work in some homes, and not in others.
Some people don’t bother to put bathroom lights on a schedule and all, they just have a lights out as part of the good night routine that turns off all the lights. Of course this works best when you’re the only person in the house!
Some people put light control under voice control and use echo.
Again, if you’re the only person in the house, you might like the “lights follow being” concept where lights turn on as you enter a room and off in the previous room. Not great if you have a new girlfriend staying over, however.
One of the issues with bathroom light is what you do when someone is taking a bath or shower. These are often read as periods of inactivity but of course you don’t want the lights to go off while someone is in the shower.
And even if you do live by yourself, you may have guests occasionally. But some people have really complex motion sensor based routines that run when they’re the only ones home, and then they have a guest mode which pretty much removes all the “turn off” functionality.
SmartThings Gives You Many Different Control Options
So, you have a lot of basic tools to work with.
You can have lights turn on and off by voice.
You could have lights turn on and off based of time of day.
You can have lights turn on and off based on whether it’s dark outside. Or based on sunrise and sunset times.
You could have lights turn on when there is activity on a motion sensor.
You can have lights turn off after a period of inactivity on a motion sensor ( this is the tricky one.)
You can have light to turn on for a fixed period of time and then turn off again (another tricky one)
You can have lights turn off when there is activity in a different room. So if there’s activity in the bedroom, turn off the bathroom light. But again, that works best if you’re the only one in the house. And if you don’t have a dog.
But Define Your Use Cases First, then Choose the Tools to Accomplish Them
But all of these are just tools. Before you can decide which ones you’re going to use design what are called “use cases.” This is just a paragraph or so explaining what’s going to happen from the persons point of view not the systems. Things like “I pull my car into the driveway and the lights come on in the garage and the kitchen.” Or, "when the bathroom door opens, the lights come on. They stay on until I tell them to turn off by voice. "
When you know what you want the system to do, you can figure out how to make it do that.