Hussar
Legend
I don't think its unreasonable for a wealthy lord to have in his service servants to maintain lamps and torches all night in certain parts of a keep or whatnot.
Lamplighters could serve a dual purpose of maintaining lamps and torches AND act as patrolling watchmen as they went about their rounds - or they could just be like candle-men and act separate from guards.
I know that I've read fantasy novels which have had scenes with watchmen/lamplighters like this but I can't think of any off the top.
Oh, and castle owners would not light torches just for show or for vanity but because it repels thieves - I had my garage and car broken into twice and the Cops said straight up that thieves are deterred far more due to light and dogs than any kind of high-tech alarm system.
The only problem with this is that the cost of keeping those areas lit is likely more than what it would cost just to let the thief get whatever it is he's going to steal. Keeping a castle lit to any signficant degree would cost a fortune.
Your guards walk along with lanterns at night. You generally wouldn't have torches all over the place to be lit. If nothing else, the fire hazard something like that would be would make it impractical. Having bunches of open flames all over your castle where you also have nice old wall hangings and rushes on the floor is a bad, bad idea.