My history is not clean (long overstay years ago), but I didn't have any issues with the DTV (I had many with tourist visas). I think it mostly depends on the immigration officer (mood)
I have entered four times so far, without any issues. Last time I arrived from India. While they asked every single male traveler for proof of accommodation and a return ticket (they even asked one for proof of funds), I was through the immigration counter in 1 minute, all the officer said, was Finiddd" :-)
Anonymer Teilnehmer 495 I know a guy who has been checked, I cant make any statement how Common this is, but I personaly think it will get more common in the future with increasing popularity of the DTV.
They will most likely not check your attendance when entering (could happen but how would they make sure you were actually there or not? If they call the Gym, make sure they hear the right answer 😉 ). Tourist police started checking attendance though, so you better start, what you signed up for.