Switch work is control rather than power delivery, and that is what makes it different from an outlet. Replacing a switch, adding a second one for the same light, putting in a dimmer, or fitting a smart switch all come down to what is inside that particular wall box. So the first thing we do is open it and look, because two boxes in the same hallway can hold entirely different wiring.
The most common surprise is the neutral. Most smart switches need a neutral conductor in the box, because the switch itself needs power to run its radio and stay online even when the light is off. A great many older county homes are wired as a switch loop: the power goes to the light fixture first, and only two conductors drop down to the switch — a hot and the switched leg, with no neutral present. There is nothing wrong with that wiring, but it means the smart switch in the box on your counter will not work in that location without a new conductor run from the fixture or the panel. That single fact decides whether your project is a straight device swap or a conductor run, and it is why we would rather open the box before quoting than after.
Dimmers are the second recurring issue. LED lamps and integrated LED fixtures do not behave like the incandescent bulbs that older dimmers were built for. The result is flickering at the low end, an audible buzz, a dimming range that stops well short of off, or lamps that will not start at all. The fix is matching the dimmer type to the driver in your fixture, setting the low-end trim once it is in, and testing it with the actual bulbs you use rather than a shop lamp. Sometimes the honest answer is that the fixture's driver is the limit and the dimmer is not going to rescue it. Our flickering lights guide covers the diagnosis.
Adding a switch where there is not one — a second control at the far end of a hall, a stairway, a bedroom doorway, a detached garage — means new conductors between the two locations, not just a device. In a house with attic or crawl access that is straightforward. Through plaster and lath with fire blocking it is a real run. Most shops will not book a truck for a single switch, which is exactly the kind of job we are built for in older homes.