My better half currently does about 400km a day in a Hiace van. Replaces 2 - 3 windscreen each year.

I do about 30,000 km per year. I bought a new car just over 4 years ago and have put three windscreens in that yet my other car which I've had for 20 years still has its original screen. Both cars used for the same driving, go figure.

I check every insurer each year to make sure I get the best deal. Up until recently I found that Trademe insurance was the cheapest, but theu have got a lot mor expensive and they no longer even offer glass cover as an option. The cheapest I found for the last two year running was Cove, plus you can get a price online and mess around with the excess and insured amount to see how it effects your premium. And yes, they offer glass cover as an optional extra.

You don't have to use this link, but if you do you will get one month free (to be transparent, and so do I)

https://coveinsurance.co.nz/referred/?code=4BA002&firstname=Matthew

They were the best for me.

Lowest premium price is not necessarily the most important thing with car (or any) insurance - you often get what you pay for. The OP is inadvertently an example here.