I havent played in a while, don't know what your rank is and the meta may have changed since I played but a couple points I would make:
in zvz extra queens work with a lot of builds, for example to ramp block against an allin, or to do an allin of your own and get creep across the map early for a roach bust.
In zvt 9 queens is great if they're going for early drops or cut macro to get hellions across early, but they're kind of a wasted investment against a macro terran. It's gonna be very specific to scouting as you said.
In ZvP having those extra queens against the double stargate *rush* is fantastic, but again it depends a little more on context. If it's a double stargate macro play where they get void ray speed early, queens are basically terrible. However if they're going for lategame carriers and your play against that is hydras, a bunch of queens to tank and transfuse while hydras burn down interceptors can be great.

It also depends on your micro; queens can stutter step kite slow zealots and shut down an early zealot rush. If you can control a group of queens seperately it's going to have a TON more value than if you're just adding queens into your army group or f2ing.

Early on, when you don't have much larvae, you can consider queens you make to be a tradeoff against tech you could have made. The obvious comparison is a queen vs making a lair. Later in the game when larvae is abundant, queens are more of a tradeoff against drones.

For me, since my scouting sucks, having extra queens to spread creep (and replace killed tumors) is critical. If you are the type of player that gets ovie speed and scouts well, maybe extra queens would be less useful.

eens and 2 groups of 3 creep queens to fight the hellions or at least that's what reynor does but they arent a waste since they're gonna be spreading creep for the rest of the game and can hold of small drops.

at m2 that sounds right to me but at a lower level like plat where maybe the opponent doesnt make hellions or drop at all, then spending on queens can put you in trouble. But of course it also depends on how hard you're droning and shit like if you go for early speedlings you don't really need the queens against hellions vs if you go for a proper early third then you won't have enough lings to chase and surround. Plus, asking a plat to have 2 extra groups of queens to control is probably a non starter haha but strategically of course you're right