Do I still need to report to immigration every time I return to Thailand for a TM30?

If returning to same address, simply register your address on the app, and use that each time. It's really very easy to use, takes two minutes and sure beats the hell out of traipsing to an immigration office

As with everything in Thailand it depends on your immigration office. Send them an email and ask. That way you have something in writing.

You need to ask your immigration office their TM30 policies. You'll need to ask this every year because each office is different and they also change their policies from time to time. There are basically 3 policies that offices follow.

1) any time you travel anywhere, both inside and outside of Thailand, you must file a new TM30 when you return home.

2) if you only travel inside Thailand, you don't need to file a new TM30 as long as you return to the same address you filed before.

3) no matter where you travel, both inside and outside of Thailand, as long as you return to the same address, you don't need to file a new TM30.

I would say #2 is the most common, followed by #1.