Hi,

I just have started working with lot. As per my understanding, before confirming the stock picking, you need to enter the lot number. So when you confirm, it will make an entry in stock quant with the correct lot id. 

Also odoo may not be able to allocate lot id in stock move because, for one item only one move line is created. And multiple lot id may be assigned to same move line. So it is better to store the lot id in pack operation and the same will be cascaded to stock quant as the stock quant is split accordingly.