NL did not ask me for insurance details when applying for a visa. I only had to give that when applying for a Thaipass. But your visa is different. I asked for non O based on visiting child.
And today again. Arrived in BKK today. Return flight in 3 weeks, health insurance 3 weeks, O visa based on visiting my child for 3 months. Stamped in for 3 months. The return flight with Etihad can be changed for free. That saves me 2 months worthless insurance.
I heard numerous stories here on Facebook that insurance did pay. Tune even pays directly to the hospital. With your insurance you can be 100% sure that you will have to pay for everything yourself.
You need insurance for the duration of your stay, and that depends on your ticket. So you can buy a ticket with a return date within 1 month, with insurance of 1 month, while you are stamped in for 3 months based on the duration of your visa.