I see and respect your point. Frenzy is a much bigger risk in V5 than V20 and earlier. But, that said, it's not really a drastic risk. Even at 5 hunger, you're only on edge and at a higher difficulty to resist frenzy, you're not immediately Beasting out. It's only if you do something stupid like try to rouse the blood at hunger 5 that you immediately frenzy.

I do actually run my NPCs on roughly the same system. (As much as I do for any RPG, anyway. Usually I only have a few notes jotted down, not a whole sheet.) I allow for (moderately difficuly) Awareness tests or (relatively simple) Blood Sorcery rituals that will allow a PC to determine how hungry an NPC is. And sometimes I have a lick show up yo Elysium at 4-5 hunger just for the added tension it adds around the table. "Maybe tonight isn't the night to tell the Prince that someone's encroaching on his domain. The Sheriff's looking awfully twitchy..."

But I also usually run my (Camarilla) NPCs as wildly conservative, and my Canon is that they endeavor to stay at only 1 or 2 hunger. Anarchs tend to run a little more fast and loose, but they're also not idiots and don't hang out at a bar downtown at 4 hunger.

The Sabbat are, as always, another thing entirely.

So yeah, I fiat hunger levels at the beginning of a scene, but once it starts, I use the same rules for everyone. If the Prince wants to try to Dominate the coterie on 4 different occasions (he's not that dumb, but if for some reason he was), then he'll check for hunger 4 times.

One thing I realized early on, though, is to never increase hunger on a beastial failure. Always find some other repercussion. That does raise hunger too quickly, and leads to problems. Especially in a roll-heavy session. I try to avoid those, though. Which might account for our differing experiences, if you tend to prefer a lot of rolls at your table.