There was one time that I didn't hear back from the lady at all. Ya know...ya never know what happens to folks. If they are very ill, had a car crash, or if they died! If I died, not one single person in my family would think to check my Ravelry! So there it would sit with dozens of messages left unanswered.
Most of the time, you hear back from a person inside a week. Some folks don't check-in to their Ravelry on a daily basis. I've set up my Ravelry messages settings so that I get the message on my email, and it boots to my smartphone. I can read the entire message, but to answer it I have to click the link and I'm booted over to my Ravelry messages.
With regards to Facebook...I only look at my FB once or twice a month. My bad, I guess.
But I have my settings set up so that I get a notification about stuff that's going on with my friends. Mostly they post very mundane stuff. With my adult kids, I'm really quite shocked at what they chose to share. It's insane.