"Don't ask to ask, just ask" is great in general, but if I tell someone this, I'm not trying to schedule a single call. It's more asking for permission to call whenever. Depending on who you and your friends are, it can be necessary to give this heads-up at least once so that, as another user put it, they don't get a panic attack from an unexpected phone call. As an older Gen Z, it feels like no one my age really calls each other out-of-the-blue, and you need something like this to establish it.