I got fed up with variacs, light bulb limiters, and meters all over the desk so i built them all into one enclosure. With the flick of a switch i can take the variac or limiter out of the circuit while the connected device is running
If you are restoring old gear a variac and limiter is a must have. Even building amps from scratch i highly recommend using them for the first power up, it has helped me catch a few mistakes in the past before i fried something.