Overcooking the zucchini strands will result in them being soggy. It's much like cooking pasta al dente. You want the strands to still have a "bite." You don't want them to be too soft. So, please don't cook them longer than necessary in the first step before adding the garlic. Then, after adding the garlic and letting it cook briefly, turn the heat off immediately.
Sometimes, I add a cup or two of shredded baked chicken breast or boiled shrimp to the noodles. This turns them from a side dish into a complete meal.
You can keep the leftovers in an airtight container in the fridge for up to four days. Reheat them, covered, in the microwave at 50% power. If you like cold leftover pasta, you'll enjoy eating these leftovers cold. I certainly do! I don't recommend freezing the leftovers.