It's important to realize that everyone has a different social contract for how quickly they expect responses across different channels. The better advice is to actually have open, honest conversations with those you work with most frequently and those with whom communication is important to define and understand how people are going to perceive those different channels and contracts.

Setting up social contracts for different communication expectations doesn't have to result in everyone having the same guidelines, but does let you know that Alice is okay with texts while Bob really prefers emails to be allow 8hrs+ for replies.