Once you get past that 'enter before' date on the visa, It's done. Finished. Can't be used again. If you enter just before that date, you get another 60 day stamp, but the visa itself is finished. The stamps you get on entry are your 'permission to stay' in Thailand (the date on those is the last day you can stay until), which can be extended, once, at an immigration office inside the country.
That's quite likely to be the reason why they limited visa exempt land border entries to two per year. To make people like this fella fly in and arrive somewhere where they've got a cell to put him in while they arrange for an airline to fly him out of the country again.
The 'overstay principle' is unpopular in most countries. It makes you an illegal immigrant. It's only kind of slightly ok in exceptional circumstances. Like if your flight leaves at 3am and your permission to stay ran out at midnight and you got delayed on your way to the airport or something. It's relatively straightforward to stay legally in a country. That's what everyone should do.
Thai embassy dot com, despite its name, is not a Thai government website. It’s a law firm which, unsurprisingly, suggests problems that can be resolved by paying lawyers.
Had my permission to stay stamp checked and a photocopy of both the ID page (which is normal) and the stamp, and the departure card taken in a hotel in Bangkok this week. All the information written down as well.
They used to just photocopy the ID page and that was it. They’re clearly being asked for more information by immigration.
If your friend is near to a border and hasn’t already done two land border crossings on a visa exempt basis already, then that could be an option. Or do the second extension request and have that denied to get the extra 7 days. I think either of those options would be better than an overstay, even of just one day. But that’s just me not being a fan of needlessly staying illegally in any country.