It depends on the number of different products that you have.
Different products = different variations
That means if you change the color, size, scent, shape, quantity, design, style, etc., then each one of those changes makes it into a different product and will need to have its own barcode number.
If you sell t-shirts in 5 different sizes and in 5 different colors then you need 25 different barcode numbers. (5 sizes x 5 colors = 25 barcodes)
If you have 100 of each size in all 5 colors you still only need 25 barcodes because you are always on going to use the same barcode number on all of the items that are identical. It does not matter if you have 1 or 10 or 10 million of a product. As long as it is the exact same (no variations) then you are going to always use the same barcode number on that product. But, as soon as you change something, it becomes a different product and needs to have a different barcode number.