Laos, soft power, approved in 4 days
Just sharing my experience here for those starting the process.
Submitted application 7 May
Paid fee (you have to do this in cash at the embassy) 8 May. Paid at 9 am (no queue at all)
Request for further documents 11 May
Approved without interview 14 May.
I submitted the bare minimum. Just one bank account with the minimum 500,000 THB (although in my case nearly double), with no income and no expense (hence reason for request additional documents, as I think they initially didn't understand the bank statement covered 5 months). Laos visa (they later also requested entry stamp, so don't forget to submit that too). Letter from Phuket Muay Thai for my 9 months course. No cover letter, no further proof of stay in Laos, nothing complicated. Just the minimum they need.
Now I am from an EU country, typically considered a strong passport country. Not sure if that contributes to a quick and easy process.
Whilst waiting I travelled around Laos and had a great time. Definitely worth going to Vang Vieng and Luang Prabang!