We have been dealing with different fabrics for over 50 years now. We know by looking at a material the saturation capabilities as well as any risks we are taking.
With new technology it has made this process much easier as the fabric inst over wet. Also if you washed your cushion covers in the washer there is a 50% or higher chance they will shrink. Many times even with that same material our equipment can clean them while still on the cushion with no problems as the foam cushioning provides enough support and added material perforation that it will hold its shape no matter what equipment we use.
The advances in technology have really added more cleaning capability, with less risk, and faster dry times.