The amount of pieces of thread is far too uncommon to find. I'm currently 6 months in and have found about 15-20 spools of thread from looting every building in the areas circled in red and the major buildings, stores and warehouses, in the area circled in green. In comparison I've found 8 generators and 12 magazinez for the M9. I'm running with the lucky trait and have found 5 sewing kits containing nothing at all. The current amount of thread makes it far too hard to level up your tailoring which I've currently leveled to just short of level 2 with having to use 12 spools of thread with varying amount of thread(uses) remaining and have also been removing patches. I get that it is not supposed to be a breeze leveling up but currently it is faaar too grindy and unreliable to the point where it feels like it is not even worth investing time in. I feel like every 1/5 houses should have some pieces of thread laying around or a sewing kit with around 3-4 pieces of thread.