"Cockpit visit" - definitely a threat at that stage of the flight QED
There are times when you have to be assertive and deny any such requests (unless for emergency reasons - ie cabin crew informing etc).
I have seen pilots become so "task saturated" that they are almost not aware what is happening. This is where PNF has to assertively step in and save the day.
Psychologists have established (and subjectively I think they are correct) that when humans become "maxed out" the first "sense" which the brain deletes is that of hearing. ie the ear (physically) hears what is being said but the brain says "hey am too busy to listen to that at the moment!".
So FOs need to be trained to do a pattern interrupt. If after (say) 2 prompts there is no response it may be necessary to actually shake the other pilot on the shoulder (say) to get his/her attention and assert in command tone "Too high - Go Around" or some such thing.
In the end it all comes down to SOPs, training and disciplined operation.