It is wise to plan and it is wise to expect your plan to fail. This is why we need to learn to be adaptable.
How do you respond when your plans fail, or when something unexpected and unwelcome occurs?
You can get angry, you can break down, you can ignore it and run. You can be led by the Spirit and be patient, trusting in God for the strength and wisdom to make it through.
Even so, spiritual planning prepares for the worst, trusts God for the best, and knows that in the end, even if all crumbles, all things still work for good for those who are in Christ.