At the end, you decide what challenge you want to take up. If you're programmer, you may want to consider only the programming time. Personally I expect to shorten the whole process, i.e. from finding the idea to releasing the packages on itch.io, because I want to become more efficient in all of that. Moreover I expect to do that every week, and time adds up quickly, but I don't want to waste a lot of time making these games, that's the reason behind the one hour rule. But for now I always exceeded.