Note: I'm aware that some countries (e.g. the USA) require you to pick up your luggage on international flights. This question assumes that there is no such legal requirement.
When booking multi-city international flights under a single reservation, under what conditions, by default, is my luggage transferred automatically across two consecutive flights? Note that these are not booked as "connecting" flights, but rather separate flights under a single booking.
For example, I imagine that if two consecutive flights are separated by 1 hour, then my luggage should be transferred automatically, but if they are separated by 1 week, then they shouldn't. So what exactly is the in-between cutoff? Is it listed on airlines' websites somewhere? Or is it listed under the fare rules? And is it something I have any control over (and if so, how do I request what should be done)?
(I'm just looking for a general rule of thumb here... if you think it differs widely across airlines or countries, then please just give a couple of contrasting examples for two popular countries or airlines.)