It depends on your vehicle.
I personally drive a van, most of the time. Checking over my shoulder is a waste of time. What I do need is situational awareness. I’m aware of where my blind spots are, both absolute (e.g. directly behind my back bumper) and partial (e.g. the spot down my side).
I try and keep an awareness of everything entering and leaving my blind spots. I also do 2 checks of all spots that could have problems when manoeuvring. It’s alarming how often a small car or bike can slip through blind spots, when you’re doing your checks.
Basically, know your vehicle, and do what’s appropriate to keep everyone safe.
My job has large patches like this. I refer to it as “fire duty”. I’m not being paid to do anything. I’m being paid to do the correct thing in an emergency. I’m the insurance.
Your best bet is to check your rules, either on paper, or to ask and do an appropriate hobby. It’s particularly effective if its a cumulative hobby (thing programming rather than computer games). If queried on it, you’re just keeping your brain up at speed.