Shipping cost

Hi, I have the following question that I would like to help me.
I have imported products and the sale price I have increased the percentage corresponding to the shipping cost, obviously this is a lot of work to do for each product and I realize that this option already exists in the plugin.
My doubt is that if I configure this option at this time and continue importing products, I will have products with the percentage calculation in the sale price and the new ones already with the shipping cost in the sale price, what would happen when the information is synchronized and updated prices, which of the two methods thata I have use will be respected?

Regards

Víctor