the terminals are your last resort if you didn't file before arrival. You'd be sent to the terminal before you get in front of an immigration officer, fill it in, get your TDAC approval sent to your email, or possibly also scan a QR code, show the officer your approval QR code.
You really don't need another TM30 filed unless you want to do some business at immigration. If you have a primary residence then file there despite where you travel around to within Thailand