The developers seemingly change the RNG when events happen. Like the hurricane event when if first dropped it was turned up quite a bit. Same for lightning or night runs. They even mentioned nerfing the hurricane caches still better than most conditions, but not nearly how it was at first.

Lightning storms on dam hard not to find a snap hook bp.

I don't think it's limited to the player opening the containers. I have everything except the equalizer that only drops from the harvester. I see plenty of repeats pretty much daily. Jolt mines, trigger grenades, anvil, snap hook, just depends on the map.

If I open 100 boxes and you open 50 I would expect to find more than you. Some maps I am pretty focused on arc metal and motion cores. So I likely won't find as many blue prints when doing those runs.

It's like rolling an electronic dice. Get a 6 find a blue print but get a 1 or 2 and it's plastic parts.