This has been my experience and is the annoying part of the butler (though in the majority of my handful of St. Regis stays, I never came into contact with the butler at all).

Once in Doha, I called down for coffee at 3:00am. It came after about 15 minutes, which is OK, but "my" butler brought it, bleary-eyed in his tuxedo. I feel they rousted him out of bed and made him throw on his uniform. He was perfectly professional about it, but I felt guilty. This was totally pointless.

As for some of the enhanced personal services, like unpacking my luggage or drawing a bath, I have absolutely no interest in someone performing these things for me. So the butler does not increase the value of the St. Regis experience in my opinion. I'd rather just have prompt, responsive service from whatever department I call.

(On a related note, I really dislike the "single point of service" that the butler service promises and other hotels use. I have commented on this in another thread somewhere. For example, InterContinental has an "instant service" button that is designed as a single portal for all of the customer's needs, but usually when I call, it rings and rings and rings, then when someone finally answers, I state my request, and the agent has to transfer my call to the relevant department, where it rings and rings and rings again before someone answers. Nothing more than a waste of time; I am perfectly capable of choosing the right button on the phone from among housekeeping, bell desk, reception, room service, etc. The single portal is a nice idea if executed properly, but more often than not, it doesn't work. Note I have had the same experience at luxury hotels like Mandarin Oriental in addition to St. Regis and lower chains like IC and Marriott.)