Yeah that’s probably a good rule of thumb. My point was with the number of sub tasks op stated they had were probably either broken up to much or the task was way too big. Like if you have chronic fatigue and standing up is a struggle your goal should not be build a colony on venus. Maybe set a goal for running a marathon. Hell maybe just set a goal to take a shower every day this week.

But I like your idea of when you think you can reasonably complete that goal stop breaking it up into further steps.