WT and WTP would not be possible because there are trip hazards all over the place - trolleys can’t be used in the cabin without proper lighting and a full service would be impossible without trolleys. In Club/First a hand-run service can be delivered in low lighting - from memory I think the standard says crew should make this judgement based on how many are eating vs want to sleep, but certainly on my flights from the US east coast they’re mainly dark from 30 mins into the flight.