If you log the time at cruise that you are in the left seat, as pilot in command, you will not get hired at you PS or anywhere.
You can put what ever pilot in command in that spot to get to the next page on the application on the computer. When it comes time to defend the pilot in command entry, the interview will be over at you PS or any airline.
If you had to divert for what ever reason at high altitude cruise while you are in the left seat, and you did not consult the captain in the bunk in the divert, you would be terminated.
If you are sitting in the left seat at high altitude cruise and believe you retain the power of pilot in command, you are thinking wrong.