Some people purchase or build a hot box. This holds a rack of screens and is enclosed. Some simple home built are made of wood. Some add in a heater with a dehumidifier and perhaps a small exhaust fan at bottom to draw out the heat with moisture.
The heat should probably not reach beyond 100 degrees. Too much heat can make emulsion go bad or contribute to other issues like cracking/baking.
As with coating techniques, it's not how many times you coat a side, but the desired thickness needed.
A well dried screen is similar in that it's not how long you let it dry, but how well.
The conditions in your drying area contribute to the speed. To get it to be faster, you add in a dehumidifier, a heater and contain/isolate that heat. If you are able to dry your screens in 20-30 minutes, that's a good decent time. I don't know if you need to get any faster. Especially if you are just starting out.
As far as time goes, some shops won't use a screen in rotation for hours or next day, and others rush it and use it much sooner than they should. Too soon, causes exposure issues and if only doing solid prints for the time being, you may not see your bad habits. When customers want you to print their more sophisticated art and you get into fine halftones, you will see these issues pop up and won't know why, since everything else has been do great in the past.
