Mystery Light Switches
If someone swiched some of the receptacles it is possible they didn't remove the tab between the brass screws and now they are not switched anymore.
Ceiling fan locations are wired for fan and lights....even tho only the fan is installed.....or even a blank cover at the ceiling location......
How about switched exterior outlets for the santa lites?
The only way to figure it out for sure is to simply test every single outlet, interior and exterior, (not just one plug in an outlet pair, but every single plug in your home), and create a map of what switch is connected to what box.