I have run that experiment. What happened with ambient air was a spool of filament in my Sunlu S2 started drying and did the initial humidity rise in the dryer thing and then it gradually started dropping. I was weighing the spool and the weight was dropping.
The weight changes got smaller and smaller until the weight quit changing over the time scale I was using - what many take as the end of a dry.
I then connected the dry air purge and spool weight started dropping again and humidity in the dryer also resumed its dropping.
In terms of dry air removing more water than just using ambient, absolutely. You can’t miss it and it’s a big effect.
I never measured the rates per se but if I look at the final weight/humidity, ambient air wan’t about to hit the same level of dryness at all so “infinite” time to dry.
Since the rate water is removed depends directly on the humidity difference, a bigger humidity difference means faster water removal rates so dry air will speed up the drying process.