Flying in to get a 30 day Exemption Entry is not officially limited but several back to back fly in entries will likely get you pulled aside and questioned or denied at some point
The 'Retirement Visa' obtained in one's Home country at a Thai Embassy or Consulate is a Non Immigrant O-A Visa (notice the 'A'), 800,000 Equivalent Thai Baht in your Home Country's currancy in your Home Country Bank.. be age 50 or over, plus a Criminal Background Check - plus a Medical Certificate both obtained in your Home Country. It has nothing to do with being in Thailand at the time.. Nor does it have anything to do with having money in a Thai bank at the time of application