{Ed wrote: This is why I asked if the wood was air dried (which would not ever be hot enough)}

So, I have access to kiln dried and air dried Scots pine, and kiln dried spruce (Picea abies). In the kiln dried ones there can be resin pockets, but they are mostly dry, so perhaps the kiln changes the properties of the resin. The air dried pine is from trees that grew above the polar circle. It has nearly no resin (apart being produced as a defence, resin formation is apparently related to growth temperatures).

The spruce is fast grown construction wood, and I suspect that the very wide tracheids and less amount of binding lignin results in the plane blade parting fibres, not by cutting, but through longitudinal splitting at deeper levels, with coarse uneven clogging “shavings” as consequence. Then again, ring porous woods like oak and ash have wide tubuli, but clogging is not problem, nor is thick shavings…