How far ahead should you plan in advance?
There's a common saying amongst hikers that goes like this, "weather doesn't change plans, it changes what you pack." The more into hiking you get, the less you plan around the weather. Rain or shine there are miles that need to be covered. Being a little damp isn't so bad, and the weather will turn eventually.
As a climber, the attitude is a little different. In the mountains, the weather changes quickly and the stakes are higher. When preparing high altitude adventures, it is useful to plan around windows of opportunity. Generally, 48 hours, or two days, is as far in advance that you can rely on a good forecast.
It's a go or no-go situation.
Looking at the challenges we face, it's useful to classify them similarly. Is it a "packing" problem, or a "window" problem?
When it's a packing problem, we should focus on the tools we need to accomplish the task and set an expectation for the amount of discomfort we're willing to accept to reach out goal.
When it's a "window" problem, we need to understand the plan and have a clear understanding of what consists of go or no-go situation. Then, when it's time to make the decision, we need to stick it to the decision process even in the face of pressure to change it.