Quite a few games (eg: Starfox) in the 90's would use BSP in a slightly different way - purely within each object. The tree would be generated offline (mechanically or by hand), and would often be some sort of branching bytecode (test this, draw that etc.)
It was very useful to be able to use one plane test to discard a whole bunch of geometry, eg: a surface plus its detail, or everything visible through a window.
This still left the problem of sorting between objects - mostly a depth sort was just fine. Special cases like weapons on hardpoints, or vehicles in hangars could be handled by having some sort of 'call submodel' for spaces within the parent model. Beyond that, just dial up the hostile firepower until players stop complaining about rendering artefacts.
It was very useful to be able to use one plane test to discard a whole bunch of geometry, eg: a surface plus its detail, or everything visible through a window.
This still left the problem of sorting between objects - mostly a depth sort was just fine. Special cases like weapons on hardpoints, or vehicles in hangars could be handled by having some sort of 'call submodel' for spaces within the parent model. Beyond that, just dial up the hostile firepower until players stop complaining about rendering artefacts.