Mostly the first ten minutes. A scheduled plumbing job starts when somebody arrives. An emergency one starts on the phone, because whether the water gets shut off in the next few minutes usually decides whether this is a repair or a rebuild. That is why the line is answered by a person at any hour rather than by a service that takes a message.
It also changes what a business has to be built around. Being genuinely available at three in the morning is not a feature added to a normal plumbing company, it is a staffing and dispatch decision that shapes everything else, and the company states that it does not add an after-hours premium for it.
The rest is ordinary trade work done properly: the diagnosis before the quote, the price in writing before the repair, and photographs of what was found. None of that is unusual. Doing it at two in the morning is.