Lord.......when I fly with other people, as a general rule...99.99% of the time...I am either PIC with a passenger up front....or as an instructor with a student...I did the performance planning...and thus I will make the call to roll it out, or fly it off....
But during the times where I have flown SIC in say a GIV or Astra...planes I wasn't trained on, I was at the mercy of the captain's decisions......to a point.....
Now oddly enough on one trip in the GIV going into LA, in a jet I had maybe, 2 hours in, SIC, Not having gone to school.....the captain got too close to a SW 737 on a visual approach....ATC warned of this....I pointed out the N NUMBERS on the jumbo jet in front to the pilot......
When the wake turbulence hit...THREE TIMES...the GIV wings went almost 90 degrees vertical..at about 45 degrees I looked at a catatonic captain...
So I pushed the yoke forward, applied enough counteracting control forces to keep the plane from flipping over....3 Times.
Of course the captain blamed it all on ATC...
So to answer your question...more directly...when flying with someone...I have no problem 'Helping' the captain make the right decision.....and taking positive control if I have to.
If that GIV was an 'Airline' hypothetically...there would have been no time for CRM, Graded Assertiveness, and little chance that an inexperienced FO would have done anything, nor recognized what to do in time to address the problem to the captain, have positive transfer of controls, ect.
I doubt you can roll a GIV at 4000 feet, at such a slow approach speed and come out of it...