Is it possible to repeatedly enter Thailand for short stays without a visa?

I've done month on and month off and 6 weeks on 3 weeks off traveling to Thailand during off time since the end of 2010.

In this time I've been stopped twice at immigration and asked questions but never been denied entry. Since the last time I got stopped I've been a bit more worried about it and I'm working on a more permanent option.

I was also here on visa exempt entries and extensions for roughly months in early 2016 as I lost my job.

You'll be absolutey fine short term to mid term, if you plan on being here and doing that for a long time then look into other options for visas to be safe.

I do 3 weeks at work, 2 weeks in Thailand and I have never had a problem. But have heard about people who have had problems at immigration

A long haul flight every two weeks would be a nightmare for me.. be prepared to having your bags searched when you come and go. Entering and leaving the country 25 times a year, could look highly suspicious.. getting a visa might help but then drug dealers have visas too.. ( I'm not saying you are one, just making the point that it could look suspicious)

I imagine there is no problem for the first few times but it does look a little bit suspicious after a while - how're you able to do this frequently/indefinitely and why (are you really a tourist?). A METV would be the safer/proper way to do this.

best bet is to get a 6 month METV prior to coming then run them back to back as many times as you can

Many people that work offshore and on rotation do this but I've heard stories about some isolated incidents with border IO's who complain and telling to get a proper visa. I'm sure there will be some with this experience pop up and adf their take on it.

Your plan seems rather expensive for no reason

Yeah, but if your aim is to stay in or around Thailand you don't have to go to Europe, just go to nearby countries.

Basically yes