When I message/call/text/email my mail friends, I know there's a 1h-24h time window before I get a response. And that's if the message prompts a response. Otherwise, they'll address it next time in person, or just let it fly by. On the other hand, my female friends respond much quicker.
At the same time, I see my current girlfriend ALWAYS on her phone. There's always someone she's in contact with - because it's a priority for her to respond. My male friends when hanging out, are almost never texting/chatting on their phone unless something immediate demands attention. It's an interesting tradeoff
For me I think the biggest barrier is housing proximity. All my friends live in different suburbs, which means on the weekend that's a 30m drive each way, and it's worse afterwork on the weekday. Sucks.