Times have changed, it seems, along with communication etiquette. Email became the primary communication method, in the 90s, often with follow up phone conversations. With email, a response was expected within a day of two but often a back and forth conversation would take place at the time if both parties were at their computers. Then when texting via cell phones became a common form of communication, more immediate responses were expected.
There are people that I communicate with solely through email and our messages to each other are sporadic. It could be weeks of even more between messages. I communicate with my inner circle of friends via phone text and phone conversations. I text throughout the day with these folks and I respond when I happen to pick up my phone and when I am not otherwise occupied, but I do respond. I don't necessarily pick up my phone every time I hear the notification that a text has arrived. I don't interrupt what I'm doing to read and respond to texts, unless a back and forth conversation is in progress and a response is time sensitive.
What I have noticed is that the younger generation seems to have a different text etiquette. They don't respond to confirm receipt of a text or plans made. I don't know, maybe it is just the young people that I know but when someone suggests we meet sonewhere, I will always respond to confirm our plans. The youngsters don't respond to confirm but show up. Is RSVP dead?