You have to open the file, find the email you were going to respond to, double check with whoever that the answer is “yes”, look up the other attorney’s phone number, double check your calendar to make sure the date works, call you spouse to make sure they can pick up the kids that day, and then call the other attorney.
If you think Biglaw clients, with in house counsel that used to be at biglaw, blindly pay padded bills at $800/hr, you are mistaken.