You can use the greatest PS in the world, and as much as you want. You can scrub until the cows come home but.......
You are paid to get rid of the dirt (extract) and everything else that you put in it. Anybody with water and a Shop Vac can "rinse" the carpet....cleaning the carpet is another matter.
You don't need as big (cfm) a machine as 5 years ago. 2.5 inch hose, a 2 inch wand, and a
glide have made a small, single wand TM so much more productive. A 45 blowe and some extra HP behind it is all you need. You do need a lot of flow if you don't want to go over the same area again and again. Just ask Ron Lippold to go back to 6 flow at 300 psi and watch what kind of face he makes.
Vac up as much dirt as possible, emulsify the dirt that is left over, and then suck it up and dry it as fast as possible. Sell clean results that last longer than 3 months and have great customer service skills......and get ready to make some bank.
The secret to success is to deliver what you promise, take the time to do the job the right way the first time, and treat your customers like you would like to be treated. Hacks soak and slither away.....professionals take their time and build their empire one custy at a time.
huuuuuu-raaaaaaaa