300D isn’t a light that I’ve seen fail on a film set, ever. It just works and works even after taking a bit of a beating. Having confidence in my gear is one of the most important intangibles as a working lighting technician.
Best boys are the second pair of eyes and hands to Gaffer or Key Light are necessary for any crew. A best boy is a crewmember who serves as the chief assistant to either a gaffer or key grip. When the best boy works with the gaffer (the head electrician and chief lighting technician), they are the best boy electric.