90 mins vs 60 mins meditation

I've been meditating for 1 hour, and I'm planning to extend it to 90 minutes. Will there be any significant change in my experience? Has anyone had a real experience with this? SHOULD I INCREASE TO 90 MINS? Follow up: Why does everyone say to do twice a day instead of once a day? In the [Vipassana 10 day retreat](https://www.dhamma.org/) , they said to not go beyond 60 mins as it will lead to different state. That's why I ask. Why is it getting more and more difficult as I am increasing the duration?