I think 10 years visas are for some "friendly" countries, others get 3 year visas if no 221g procedure was involved.
It's based on a subjective risk assessment. For example, middle aged Indians are usually issued 10 year visas to visit their children in the US.
Re:To Conference Organisers Everywhere
by fdgjgbdfhgb on Monday August 21, 2023 @07:13AM
(#37207937)
I (Brazilian) had to get a J1 for a 3-month internship despite having a B1, my sister had a 6-month J1 for another exchange, so I guess it can vary
I guess the 30 Days visa are J visa ?