Planning is critical, but as the famous strategist Carl von Clausewitz warns

No campaign plan survives first contact with the enemy

So its not a huge waste of time for planning how to initially attack the problems. But likely a waste of time for documenting your code for future programmers. To use a military metaphor, you need a battle plan, but you wouldn't give that plan to historians to use as an after action report.

More concretely, you can use these diagrams to communicate your intentions amongst your team and think about your plan of attack. But odds are that what you come up with will need to be tweaked as you code and learn more about the problem. Almost always your initial plan/design needs to be altered because you can't know everything up front.

Planning is critical, but as the famous strategist Carl von Clausewitz warns

No campaign plan survives first contact with the enemy

So its not a huge waste of time for planning how to initially attack the problems. But likely a waste of time for documenting your code for future programmers. To use a military metaphor, you need a battle plan, but you wouldn't give that plan to historians to use as an after action report.

More concretely, you can use these diagrams to communicate your intentions amongst your team and think about your plan of attack before and during the project. But odds are that what you come up with will need to be tweaked as you code and learn more about the problem. Almost always your initial plan/design needs to be altered because you can't know everything up front.