Hi,
But, I don't understand why you are apply discount on each products. I don't understand why you said it's not flexible.
You can apply the discount on a category and all products which are in this category would have the discount.
So, you can open your product, add a category, select the category "discount 10%" and the product would have the discount !
And if you want to apply a discount of 10% on all products, just have to select the category "product category" and say that you want to include sub categories.
So, all products in the "main product category" (so, all your products) would have the discount. No ?
Regards,