Just bought a crank drive this year but yet to size up all the fittings on the bike.To throw a spanner in the works as it were ...has anyone mentioned the nut on hub motors (assuming you are using a hub drive) is usually 18 mm?
I commute over 20 miles each day. I rarely carry any tools, not even a pump or repair kit. Modern puncture resistant tyres mean you almost never get a puncture and I keep the bike in a good state before I ride.
I wouldn't over think it, unless you are travelling long distance into the back of beyond.
My old carrera bike has a hub drive and it's tighten to 40nm so trying to shift that without the correct tools would potentially be a problem, also putting it back without tighten it up correctly could lead to disaster.