Under the new provisions of the Visa Exemption Rule (VER), visitors can now come regularly to Thailand without limiting their stay within a total of 90 days in a six-month period. Just keep in mind that under the VER, you are allowed 30 days maximum on each visit.
The restriction has already been abolished so tourists can now visit Thailand as often as they want, provided that they obtain 30 day Visa on Arrival at airports and 15 day Visa on Arrival if they are traveling via land borders. Thai Immigration Laws are revised on a regular basis for the convenience of tourists. However, immigration officials still recommend getting visas prior to arrival in Thailand, as they remind visitors that back-to-back short visas are not the proper way to extend the stay in the country on a long-term basis.