I've found that most product clients will want an all-encompassing price. You can usually figure out what the client is most likely to use the photos for and give a price based on that. If you start charging them for every single usage, it's likely to confuse them and they may look elsewhere.
I've shot product for a clothing company and a car parts company. I knew ahead of time that the clothing company would be using it in all their magazine ads / catalog / on their website, although I didn't know which magazines they would be buying ahead of time. The auto parts company used the images for catalog / website, and as small images in certain magazine ads. I knew neither company was likely to use my images on a billboard in times square, or in print ads internationally. The clothing company only needed image rights for 6 to 9 months (as closing is often seasonal), where as the car parts company is likely to use the images prominently for the first 6 months to a year (when the products are new) then smaller images on an ongoing basis while they still manufacture that part. My pricing reflected these usages accordingly even though this wasn't explicitly spelled out in either contract.