Asking open questions is a very good communication tactic in any country. In "yes" countries like India, Japan, China it's necessary. In other countries you often find out about whether your communication partner actually understood your question.

Don't ask "Did you finish task X". Ask "what did you do on task X?". What you see as finished and what the other person sees as finished might be separate things. Maybe you see 100% unit tested, reviewed and documented as finished, and the other person means feature complete, but untested, undocumented, not reviewed.

Open questions allow you to see what the other person understands. In some cases they might misunderstand your question entirely.

I absolutely agree, plus asking "How much of task X could you already do?" is perceived as less aggressive than "Did you finish task X already?".

it's part of the culture to be nice (to strangers) and NO is considered rude. brings a lot of funky and frustrating moments not only when travelling.

another is that strange indian head-shake that is so hard to reproduce - never figured it out completely, but it felt like when I eventually ask yes/no question and they say yes with that shake, it's actually more like no/don't know/maybe

Just make an 8 with your nose. :-)

The old bobble head :) I was there for a month, the whole country, and it's their form of agreement/understanding. Particularly when you're trying to teach them something.

The head bobble just means that they hear you. It does not mean yes or no or anything else really.

There are 3 different movements. One is for acknowledgement, other two are for yes and no.

I have heard so many people say "I am not sure" and i have heard so many people say "No" and i have also heard some people say No and this is how you have to get to your destination or get to your answer.

So you are 100% wrong when you say "The answer to Y/N question is always yes in India".

Which makes me doubt/ blindly ignore any of your opinion ever.