How many times can I reuse coffee?

Online Answer
Don't tamp the second time. If using your grounds for espresso, don't even bother to reuse them. The resulting brew will not taste good anyway because the grounds have already been weakened. Don't reuse more than two times..
Related Questions 📌
Our recommendation: With breaded and battered foods, reuse oil three or four times. With cleaner-frying items such as potato chips, it's fine to reuse oil at least eight times—and likely far longer, especially if you're replenishing it with some fresh oil.
Few members of the egg-consuming public understand that, once used, an egg carton should not be reused and should be discarded. According to the U.S. Department of Agriculture's Food Safety and Inspection Service, egg cartons are considered one-time-use packaging, similar to foam meat trays and plastic wrap.
But Le Creuset makes a limited lifetime guarantee on all of its cast iron products, meaning if the heavy pot somehow breaks during normal use in the kitchen, the brand will send you a replacement free of charge.
Use Your Stove. Turns out the best way to reheat those fries so that they're not just edible but absolutely delicious is to reheat them on your stovetop, just as you would with your leftover pizza. Spread them out in your best heavy skillet to ensure maximum crispiness (cast iron being the sine qua non, of course).
Investing in this kind of cookware is completely worth it if you spend a lot of time in the kitchen or use your dutch oven more than once a week. It uses only the best materials, and your Le Creuset collection will only get more valuable over time, especially if you've collected some hard to find pieces.