Threading into plastic with no hole ?

Hello, there's data available online about threaded inserts versus screwing into a hole the size of the screw's minor diameter, which shows screwing in a hole to be almost as effective as threaded inserts for pull-out tests (and probably far more than ever necessary anyway), but bad for torque, as one may expect, however I found little info about screwing into the plastic directly.

I'm wondering about that in the context of printing 2 parts where the placement of the 2nd part relative to the first is decided after the print.

Does anyone have data or experience with doing that ? I'm primarily wondering about infill type, infill %, preferred material.

I figure you want the receiving part to be as dense as possible in the screw thread depth, but have enough free space to receive the plastic that's displaced by the screw, or else the receiving plate would break / stop being flat.

So you'd need partial infill, somewhere around 60~70% ? And if you need infill you must pick its type. You wouldn't want the pattern to be static through the Z axis (e.g hexagons) or some spots would be better than others for the screw to go in. So I guess octet would be good ? As for material, any reason not to use PLA ? (aside from other constraints of the project)

If anyone looked into this, would very much appreciate your experiences regarding these questions & other things that stood out to you.