That depends on what’s in it. Wet food (eg: a sandwich) absolutely do not reuse, throw that shit out. Dry food (eg: pretzels) can be used a couple of times or until visible wear is on the bag. Hardware: screws, nails, other nonsense, etc you can reuse until you’ve got holes.

I don’t like using ziploc bags because they’re intended to be disposed afterwards, generating lots of garbage. Instead I reuse hard containers. For example, my freezer is full of ice cream pots with tomato paste, cat food, lime juice, sauce, things like this. It’s still plastic but it fits better the two first R’s (reduce, reuse).