I really can't see any crew from any company allowing something secondary like briefing pax to affect the way they plan their flights. The plan takes as long as it takes.
A quick single stop Forties with a light load on a gin clear solid coastal day does not take long. A multiple stop, tight fuel, big loads, poor weather, changing diversions etc etc flight takes much longer. If the flight goes late because it has taken a long time to ensure that the plan is absolutely right, so be it.
It's quite insulting to suggest that the crews would allow the conduct of their flights to be compromised that way.