I have been in business for thirty years. I first started cleaning carpets with large portable machines and shampooing buffer. After four years, I bought a truck-mounted steam cleaner and that's when I learned that it was the only way to clean carpets. Trying to clean carpets with a portable rental unit is a joke. Truck-mounted steam cleaners not only remove most spots but also kill 95% of bacteria. The vacuum of the unit will make drying time much faster. Your carpet will naturally smell better after bacteria is removed.
All of my employees are fully trained. We use two men at each job and move most furniture before cleaning (and move it back).