I sounds maybe like you were approaching this as a CFI and not as a pilot monitoring? Touching the throttles of the PF is enough to get slapped John Wayne style, IMO. Not running the checklists for him... that's like 90% of your job. You need to decide if you're the PM, the CFI or the passenger.
Unless I just said "Set power" or "Climb power," but that's why we have an SOP. Touching the PLs other than to trim = instant beeyotch slap from the other seat.
"After takeoff check." "Yes, Your Airworthiness!"
That is a pretty good question at any level of experience. It's easier in a well defined crew operation where the PF's and the PNF's have a script to follow. It becomes more difficult in an ill defined environment.
A lot of truth is conveyed in the form of humor. This is a little dated, but I remember many times hearing about the three most dangerous things in aviation. They were a doctor in a V tailed Bonanza, an airline pilot in a Pitts, and two flight instructors in a Cessna 150. That last one of the three speaks to several issues, not the least of which is the CRM issue.
"Who's flying this thing?"
In all cases, I think the single most important key to crew effectiveness is open and honest communication in both directions.
Yup. Defined roles and duties also make it easier, too.
I have a couple of buddies I go fly with on a regular basis; we both have our defined expectations of what the other guy will and will not do and whose name is on the paperwork, too. We rehash them when we get in the airplane (generally the other guy looks for other airplanes).
In short, if you are going to be flying a crewed airplane now, expect to be bored even more. Now duty gets split between two people, so you have even less to do.
That's funny.
Without getting into the "any airplane can be flown single pilot and all FOs are useless baggage" argument promulgated and propagated by the chest-thumpers, there are a number of good reasons why crewed airplanes have crews, and a lot of it in my book has to do with making sure that at least one pilot is "minding the shop" with regard to positive aircraft control and terrain separation at all times, especially when things go pear-shaped.
(This wasn't always the industry's understanding; Pan American and others crashing perfectly good airplanes had something to do with this understanding being developed, though.)
A second set of eyes and hands that are trained to work with the first set is invaluable. Especially at night, in mountainous terrain and miserable weather. Of
course you COULD do it by yourself, but why would you? If the operation requires (or provides) two pilots, use "all available resources..."