The geometry of a flat underside meeting a flat pocket which is pressing down onto a 15degree face means that the failure mode of pulling through the pocket is a very unusual occurrence, the thread stripping in the wood so not gripping is more usual, but still uncommon.
But change one of those (tapered underside of the screw, tapered hole or, deadly, both ) and pulling through becomes almost the default failure mode.
I have found 1 more failure mode.
last night I was making a test joint in a piece of rubberwood sheet material. So I decided on a little experiment, the panel pieces are 20mm and are cut from pieces that are going to be drawer sides, they are really a bit too thick in my opinion but SWMBO said that they are the size she wants so who am I to argue
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to get back to the test, with 3 pockets in the end of a test piece (end grain) joining to the side of the other, drilled using a Kreg bit and a Kreg jig.
The first correct length 1 ¼ Kreg course thread screw was driven with a clutch drive drill/driver
The second correct length 1 ¼ Kreg course thread screw was driven with an impact driver set on gorilla strength and failed by stripping the thread it cut into the wood
The third incorrect length 1 ½ Kreg course thread screw was driven with an impact driver again set on gorilla strength and failed by the new mode of shearing off where the thread starts.
None of these had a pocket failure despite the excessive force used. This doesn’t rule out pocket failure if the pockets are in a more fragile material like a cheap plywood but a reasonable quality plywood will almost certainly not fail. that is using the correct drill bit jig and sensible driving force, leaving the gorilla in the zoo.
Rubber wood is a softish hardwood but a bit harder than most pines. It is a reasonable material almost white and the 2440 x 1200 sheets are made from short finger jointed pieces, unfortunately like any wide flat wood it can cup or bow here it is in the unfinished state
then with a coloured shellac base