As a long time FO, here is my perspective....this became very apparent just a few years back in my narrow body days when the Capt / FO mix was way off balance and my 4 day trip with 8 legs would have 7 Captains (NSTFS).

If God forbid we had to actually high speed reject for some fire issue...."fog of war"....I'm left wondering "is this the Captain that wanted me to talk to Tower and roll the trucks or is this the one that wanted me to make the PA so he could talk to tower and start commanding the fire fighting / evacuation?" Then "Is this the Captain that wanted me to automatically put the flaps to 40 just in case of passenger initiated evacuation or is this the Captain that wanted to do it himself after he evaluated the door page?"

I could go on....this is the stuff that needs to be standardized so it's muscle memory when the actual fog of war happens.....and it's these cats/dogs that make the "A" part of the WARTS brief be not-brief.

And don't get me started on the "I have the aircraft...but I really don't.....I just said it but don't mean it yet so wait until you think you feel me on the controls, even if you are fighting a boot full of rudder to keep us on the pavement".

I have been taught since my C-152 days and then an entire career in the fast jet world that when the PIC says "I have the aircraft/controls", then your only job in life is to let go so you aren't interfering with the PIC's inputs. Saying "I have the aircraft" is a definitive statement that should *not* leave room for interpretation from the pilot that was flying but is now supposed to be giving up the controls!