I have yet to pull the trigger on any Amazon subscription purchases myself. Seems perfect for something like cat litter where you kinda know you're definitely going to use x amount everyday, but for most things I feel like I don't have a definite daily usage and subscribing to them will end up with too much coming too soon, or not enough coming too late.

But that's a knock on me, not the subscription service. If I kept better track and knew for sure that I use 1/60th of a 12 ounce bottle of shampoo everyday, or whatever, then I'd be more inclined to subscribe to that once every two months.

Yeah I drink a consistent amount of Monster every day, and I work out very regularly. I have subscriptions for Monster and for my particular brand of whey. I can't think of anything else -- though cat litter is a perfect example, too -- that I'd sign up for a subscription for. Even my deodorant seems to be used at different rates.