Leaving/Coming back to TW for new landing visa

What, if any, rules are there about leaving TW, only to return on the next available flight just to get a new landing visa?

Here’s the story. A teacher we would like to hire has been in TW for two months. After the first 30 day LV, he left to HK and returned the same day, got a new 30 day landing visa, kept travelling. No teaching at all. He has decided to stay but his 2cd LV is up in two weeks, not enough time to get the ARC paperwork done. So, he wants to fly to HK again, turn around and return within 4 hours. Once he’s back, we can use the 30 days to get his ARC.

Am I missing something here? There should be no problem at TW customs, right? After all, a landing visa is just that, and he hasn’t been going back and forth for a year, which would look strange. Or am I being naive?

TIA

I’ve been told that a landing visa can not be used when applying for an ARC. Is this not correct?

Well, he may have to make another run to pick up his work visa, but now, I’d like him here to get settled, etc…

so no, I do not intend or think that the LV get be used to get the ARC.