You need to be careful with that. If you go with a blunt solution by turning it off where it comes in from the street and you have a boiler you're stopping the system from getting makeup water which can damage it.

You should be using a shutoff where you can isolate pipes vulnerable to freezing (e.g. running in outside walls), but it's also important to open the fixture at the "user" end as the water can still freeze and expand which can burst the pipe still.