Insight is tricky, it's hard to predict, and harder to encourage, particularly when you're fixated on seeing a problem from the same ineffective perspective.
Two, two, three, four, five, six, seven, eight, then three, two, three, four, five, six, seven, eight, and so on.
This could still take a really long time, but you are guaranteed to find the right solution eventually.
You know exactly what you're starting with and exactly how you wanna end up.
Ill-defined problems, on the other hand, have a more ambiguous starting and or ending point, such as how to live a happy life.