In fact, based on my experience, it also based on the contracted ground staff (if it is not the airline hub) mood...

For example, the manchester agent refuse to interline my QR, MH separate ticket. In Changi, the ground staff only willing to interline two separate MH ticket if each flight is not more than 12 hours apart (or depart before noon next day).

For some airport, the ground agent would ask my final destination, and some time they directly offer if I wish to directly check my bag until my final destination even if separate ticket.