Some of the bigger TMs, like my new Blueline Thermal Wave 2 Vortek, dont have a throttle and instead have three fixed switches - I, 2 and 3 or Upholstery, Single Wand and Dual Wand. Most operators including myself do runs of up to 200ft for carpet using the lowest or Upholstery setting as this is very sufficient. Mine has a 5 series blower, prior to this I had a TM with a 3 series blower which I ran flat out at 3,400 revs on carpets and 2,900 on Upholstery. On Upholstery with my new TM, I sometimes feel the vac power is too much, but I dont have a lower setting, so find myself using the vacuum relief on the tool head for the first time ever on occasions. Its all about gettiong the best out of the equipment that you have, and you can great resulst and short drying times by adapting techniques to suite.
Dave.