How long does pasty butt take to kill a chick?

[Froh]

I am wondering what the maximum amount of time is to catch and treat pasty butt until it becomes lethal to the chick. Just woke up today and found one chick squatting down with pasty butt and quickly cleaned it off, but I wasnt sure if the problem had persisted overnight already. Since clearing the vent, the chick relieved itself multiple times and has just been standing still and resting since. Will he be okay? I am also mostly asking to determine whether I should just move the brooder into my room and have constant checkups on them, at the cost of sleep and maybe some sanity.
The chick in question is a silver crested polish male, probably a few days old since he just arrived in the mail yesterday. The brooder temperature seems to be fine considering the other chicks do not have the same issue, and they are free to move around the heat source to their liking.
Thanks!

 

[Kiki]

Do you have a thermometer in there?

 

[Froh]

We do not, have been measuring the right level of heat based on their behavior in there and how we've had it set up for the chicks in the past