Overall It depends upon the Product Market Demand, if a Product is one of Trending Product, There is a High Chance, it is in a Good Quantity. So for Limited Products we Keep Stock for rest To Store Such a Large no. of Products in Good Quantity, Put Pressure on our Resources from which we can Continuously Manufacture new Sample, Complete Order.
In the End Not Keeping Stock is Good for Customer because if a Customer Require Changes on a Product it can be done Easily with Cost Effectiveness.