Is 35% windshield and 20% on sides/rear too dark?

I currently have no tint on any windows. Ive driven around a few times in a car that has 5% on sides/rear and no tint on the windhsield. The 5% was definitely too dark at night but no problem during the day. For that reason I want 20% on the sides/rear, mostly for privacy reasons. I see so much debate about 35% on the windshield. Some say its no problem at all at night and others say its hazardous and way too dark. Which one is it?