Whenever I get asked this question, I’m reminded of a sort of idiom question in the British vernacular that I’ve never heard in US culture: how long is a piece of string? That’s a hard question to answer. It requires detailed understanding to be able to answer – and that’s how it’s used in the idiom. There really isn’t one answer, strings can be most lengths. Now I realize that answer is glib, but it at least provides some context before weighing in on an attempt at some guidance.