I’m new to SmartThings, looking to change from an Insteon setup with ~10 light switches over to a more modern and less fragile technology. A core setup that I have been doing with Insteon is 3 separate physical dimmers in a living room that each switch a circuit of recessed lights. In insteon I grouped these switches together that each one of them would switch all 3 circuits together on and off. I also had the option with a remote to individually switch the circuits on and off.
Is this possible with SmartThings/ZWave? What is the lag in such a setup, do all circuits switch simultaneous?
Are you looking for a physical switch, or a virtual/software switch?
If it is physical, you could use something like an Aeon Labs Minimote to toggle switches on/off.
If you want to control with a software switch then there are several options to control them simultaneously.
You could use the Smart Lighting app that @JDRoberts suggested to turn switches on when another switch is turned on. You may need 1 copy of this app for each controlling switch.
Create Scenes that control the on/off state and dimming levels of your switches for different routines to use. Scenes can also be used by apps like the Smart Lighting app. This makes sense in instances where you want to create the same combination (e.g. all 3 circuits on/off) with several different actions (e.g 3 different physical switches).