I disagree that it is necessarily toxic. We have a similar issue where I work and I feel our collaborative culture is fantastic. What gets in our way is you can't expect someone to drop the code they are writing and context switch every time a CR is needed. So the CR happens at the next available context switch from whoever context switches first. Sometimes that means CRs are near instantly picked up. Sometimes they are picked up the next morning, usually because it is possible that the CR request got lost in the noise of our chat room. This will get caught in the morning stand up.