Off topic (but what thread stays on topic?):
Every business is going to require adjustments from what others do, and there's something to learn from everyone. There's a non-janitorial cleaning company that runs large truck-mounts in Mitsubishi crew cab box trucks so they can have five guys and one truck at a job site, and another that runs no trucks at all.
While there are valid reasons to run two-man crews, and Hagopian's model obviously works, sometimes an owner uses silly "second man benefits" as an excuse to put a E-Z band-aid on a problem that needs to be addressed somewhere else in their business system. The type of work you do, your area, the labor force available, and even the amount of room you have to park trucks will have much to do with what would work best for you. Just be honest with yourself about your decisions.
In our case, doing mainly high end residential work, we found adding a second man would increase cleaning time/efficiency 30-35% over a solo tech. While this is an increase of efficiency for the truck/unit, labor costs are much higher than the cost of adding another truck. Adding a truck gives you 100% more cleaning time/efficiency with the same labor costs as a two-man crew, so is more profitable. Having more vehicles gives you more flexibility in routing work, so drive times and related costs can be lower as well.
More guys in the house, faster speeds, and more sales pitches would make us look just like the coupon and 35% off franchises that our customers are avoiding, so one tech per truck works better for us.