Theres absolutely no indication from the films that her perception is on and in use 24/7. If that were true shed be invisible all the time.
She can react to a bullet anytime, but thats different. Daredevil can also sense and react to bullets coming from behind anytime (and slo-mo perception wouldnt help you see from behind anyway).
But h1 will pointlessly and relentlessly argue this for pages and pages.
Perception is what she sees. Are you saying she would remain frozen and helpless while perceiving an attack (that's moving magnitudes slower than a bullet) as almost frozen?
When bullets are slowed down in the movie, the audience can see her every move clearly.
Firstly I think these creatures are too fast and sneaky to be completely frozen to her.
Second there's zero evidence the world is frozen to her 24/7.
She's not been consistently portrayed the way (for instance) Clark from Smallville or Superman from Lois and Clark were. Or even the Flash. She's only shown she can move at super speeds for short bursts.
1. They are magnitudes slower than a bullet. If they aren't frozen, they move at the speed of a sloth. They don't just sneak up on people; she has to make a sound for them to attack. She knows their weakness and understands that sounds attract them. Additionally, she is too durable to be significantly harmed by their attacks, as she has withstood strikes from beings far more powerful than the Death Angels.
2. You are creating a strawman with the 24/7 argument. In battle, when attacks are launched at her, she perceives them far slower than any human, to the point where a bullet appears in slow motion. What happens outside of battle or when not under attack is irrelevant. This is fiction, and all speedsters face that problem. How do they communicate with others when they perceive things as almost frozen? I posted a video explaining this.
3. Another irrelevant strawman. She consistently perceives bullets in slow motion and has blocked countless bullets. The only time one hit her was when she was weakened and losing her powers. It is illogical to always perceive bullets as moving in slow motion and not view much slower attacks as moving even slower. That's all that matters.
4. Perception is key, not just speed. If I can perceive Prime Floyd Mayweather's punches as moving at 1 mph, I would easily avoid and counter his attacks without increasing my own speed. I would dominate him. Similarly, as long as she perceives their movements to be so slow that she can easily evade or kill them beforehand, she will prevail.
Regarding her assumed short-burst speed, she can literally kill a dozen of them in a second. No more than that would be attacking her simultaneously. Remember, they are blind and use sound to track people. Making a sound would only attract one to a dozen of them. Plus, thunderclapping her bracelets would kill a massive number at once, and she can spam that attack repeatedly.