I'm gonna get all boring and technical here for a minute. Those with low attention spans go make a cuppa
Just picking up on the point of "less suction" that some people refer to, I think it's funny how nearly all of us use extraction systems, but how many actually understand the physics of what's going on at the end of the wand
When using a glide (on most carpets) it feels like there's "less suction" because the glide is stopping lock-down - the thing that gives the ILLUSION of "good suction". When you've got lock-down you're not achieving much, simple as that.
No matter whether you're using a 3 wand-capable truckmount or a twin-vac portable, a glide helps it work more efficiently by maintaining the air flow.
More air flow = more moisture removal = cleaner carpet = shorter drying time.
Another common myth is that glides somehow "increase" airflow. You can't get 500cfm out of a 400cfm blower, that's stupid, but what you can do with a glide is make the system work much closer to its potential maximum. After an hour of cleaning with a glide, you've moved much more air through your system than suffering lock-down without a glide, so it stands to reason that you'll have removed more from the carpet.
When you first use a glide it feels VERY weird because there's so little resistance you think something's wrong. But then after you've cleaned a few carpets and noticed they all end up spankingly clean, dry in record time and your back doesn't hurt any more.... suddenly it all makes sense