For a 1 hour process why not just launch an instance ? You can also probably use a spot instance to be even cheaper.
If you're running a predictable process and you know how long it'll take in advance, an instance may make sense. If you're running an unpredictable process, where you won't know how long it'll take until it's done, and it might be quite fast, the low startup time and fine-granularity billing helps.