Maximum queue I’ve ever seen was 6 or 8 people. And the guys help with everything including getting a bank statement that I forgot. He did it in my banking app and sent it to their printer.
I’ve extended a few time over the years. Extending after the first time takes about 10 minutes work for the officer. You wait much longer in line than the actual work ;)
That’s why you can do it on the last day (which is not advised if you’re not 100% prepared).
Hahaha! Must have been the last booth north of Bangkok. They got me twice there. Since then I’m taking the leftmost lane leading to another booth apart from the main.