How many border runs can you do in a row - with tourists visiting me my schedule is a bit all over the place and need to do a urgent run before I re-start the family visa process. Don't have a day to stay so cross over and return.

There is a thought - why even enter Laos? SJust get the bus back - you have "left thailand" ?

There is no limit, but you will only get 15 days at a land border crossing (30 days if you arrive by air).

You will have a problem with Thai immigration if you don't enter Laos, although you have 'left' Thailand and been stamped out you need to have a stamp into another country.

Moved to Thai visas, residency and work permits.

There is no limit on the number of visa exempt entries by air, but 4 back to back visa exempt entries at land border is likely to lead to immigration questioning what you are doing. As said, you must make sure you get entry/exit stamp from the country you are entering/departing, or you will be detained at the Thai border on return.

But don't forget to get the exempt stamp on re-entry he will need a ticket out of Thailand within the permitted to stay period.

Not true - there is no such check for onward ticket at borders to obtain visa exempt stamp.