Yes, I get it, people are busy. But they still have time. The average citizen spends several hours per day passively consuming entertainment. You may even have spare moments at work or in a commute.
You can call your friend. Or send a quick message to do some slow chat. And even in hectic schedules you can meet once a week or even once a month.
When you haven't connected to a friend in months, you're a shitty friend. You don't have a time problem, you have a priority problem. And that's the thing that people are unwilling to admit: it's just less important after a certain age, where we use time as an excuse.