As a great example - the Covington kid video.
If you watch the full, unedited video it's actually very easy to see the situation was far more complex than the media portrayed it to be: A crowd of young kids wearing Trump hats (distateful to say the least, and a powderkeg of a situation), some _actual_ black supremacists (the Black Israelites) spouting off some real hate, and a smaller group of indigenous protesters. This was a recipe for bad interactions, but in reality the kid (Nicholas Sandmann) that got all the online hate appeared to be trying to keep the peace (getting his friend to stop doing the tomahawk chop), and was confronted somewhat aggressively by a grown adult (Nathan Phillips).
There's more nuance to be had of course (and those kids should not have been there, wow!), but the media got it completely backwards based on some very creative editing apparently to support a given narrative.
Cancel culture in this case turned the mob against that kid. With little to no understanding of the actual situation, and based only on the most superficial stereotypes (red trump hat, conservative, probably doesn't like indigenous people, etc). I'll admit even I fell for that trap before I watched the whole video. It is simply unfair and inappropriate to target a CHILD who happened to get caught up in this crazyness. We have a young offenders act in my country for exactly this reason. And the amount of hate he got was incredible.
So yes, cancel culture has, does, and will continue to make mistakes. "How much time and effort" should you go to to not ruin an innocent person's life?
I don't know, but you should at the very least make an effort to get informed on the situation via multiple sources before you break out the daggers. And be aware that you're being fed a diet of what is often corporate misinformation.