Can I enter Thailand more than twice a year by air?

I think it means on more than 120 days in total in a full year. Which is 2x 60 days. But if you come 6 x for just 14 days. Then OK. Like Europe 90 days on arrival but no more then 90 days in every 180 days.

Yes, you are entitled to enter 2 times using visa exempt if your from a qualifying country and have the supporting criteria if asked without any issue.

You can enter using exempt more than your entitlement but it becomes a matter for the passport officers discretion based on your travel history using exempt. (Eg you spend less time abroad than in Thailand, so ok).

2 maxed out exempt entries with maxed out extensions is going to equal 180 days in the future, so this will lead to a lot more conversations at passport control for 3rd attempts.

By air is virtually unlimited. Up to the customs officer whether he wants to ask questions if you really fly in and out a lot.

Over land border there was a limit of twice visa exempt crossings per year, but this seems to have just been lifted.

The entry requires differ by nationality. You may want to state your nationality to get more accurate answers.

You heard wrong you can come

The information given to you is incorrect.

Our friend works off shore works 3 weeks then back to Thailand about 6 times so no worries obviously need a visa if staying longer than 30 days

Damn I be buggered if that was true as I go for 2 weeks every month.

No such rule exists.