I tswitched into finite veins mode, installed multiple drilling machines in a single chunk and let them drain the whole ore vein. I don't know if this happens only with multiple drills or not, but i somehow managed to reach -1 ores remaining. The number then refused to decrease further, but all drills were still mining and generating ores like nothing happened.

Upon further testing i noticed that this unintended behavior stops after reloading the world, so i can only assume the chunks need to be reloaded for the drills to update accordingly