Just closed the under consideration loop in CM (Covid Extension). There was about 15 people. No lines they just asked everyone to run up and hand over the passport.
It took about 25 min from handing over passport to getting it back. Didn't need anything and I wasn't asked any questions.
Stamp good until March 30th.
TLDR : Answer Summary
The user shared their experience with the Covid Extension process in Chiang Mai, noting that it was quick and straightforward. They reported no lines, as individuals were asked to submit their passports directly. The total time taken was about 25 minutes, with no additional questions or materials required. The stamp provided is valid until March 30th.