As for 3 to 4 hours per dirty suite, never takes longer than an hour even on suites we though were brown, but turned out to be gold, dry foam imo is the quickest drying times.
Used to clean a toatl of 8 suites and 8 carpets in one 9 hour day, could allways clean at least 5 suies a day and make money, and do a fantastic job, thats why we have been going for 55 years, not tring to sound big headed, have a 6000 sq metre factory for at one time just carpet cleaning.
Did look at Von Schrader, but liked the more quite dry fusion, do agree about bigger brushes on v s sytem, but working on that getting bigger better brushes made
idealrob