I think a briefing can be short after the first flight.
for the first flight,it' s good to go deeper on details, specially with a new capt./copilot.
we all know the usual mistakes(not set the break after abort t/o, evac check list only when VISUAL fire confirmed, not read t/off checklist before reading status, ecam action below 400).
I think a briefing should not take more than 2-3 minutes and avoid the usual bla bla bla....
1 minute to go through the fmcg with the route to fly and check all pages, 1 minute for take off emergency, rtb with 1 engine, and maybe another minute for cockpit check,... that everything is here,... altitude in the FCU, radio on, squawk set, etc...
then "before start c/l down to the line".