SAS says
Doing a formal debrief immediately after the first solo isn't professional. It's ludicrous. Just because it says that you should do something in the manual, doesn't mean it's a good idea. A lack of "interest"? A lack of interest in what?
I have never seen a requirement in a manual for a formal first solo de-brief but it is something I believe is important and would be better carried out in the school immediately after the flight, not down the pub as SAS has suggested, although I understand he is probably anxious to provide a casual celebratory atmosphere.
In my experience a FS student wants to immeadiately talk about the detail asap, so why not de brief straight away combining formality and informality at the same time. Delaying that briefing, in my opinion, could send the wrong signal to the student and be interpreted as 'lack of interest'--What do you think?
There certainly is a time for celebration in the pub but thats after the hangar doors have been closed!