This is BAD advice. Always start with something generic. 99.99% of the time it doens't matter, but you need to be in the habit. Otherwise you will be in that .001% of the time where you send "Hey, how’s it going? About the plan to fire lay off Joe" and it turns out Joe is physically standing next to your target and sees the message. Maybe it never happens to you, but better to give the other person time to respond "in a meeting" letting you know not to discuss a sensitive topic right now.