Land crossing x2 per year (1st jan to 31st dec) by air is until the immigration decides your living there on tourists visas…so it won’t be unlimited times….at a wild guess id say you’d probably get away with around 9 months stay until they stop you entering
If you have left Thailand you have been stamped out and your 60 day visa is now done,you re enter with a 30 day visa free stamp,your tm 30 also needs to be re done that cancelled when you left…if you want to stay past 30 days you can now go to io for 30 days extension