I still find plans to be useful for big changes. I first ask to create a plan for the specific feature i have in mind. Then i ask for a second round of research with the current project in mind. Then i ask if it can make improvements on the plan. Then i read the plan and note issues down and let it correct them.

In my experience the problem with plans is that llms (at least gpt and claude) are really lazy and will stop at the first solution without even understanding your project. I had plans that wanted to add a few thousand lines of code just to support a very minimal part of a feature. After asking for a second round of research with the project specific limitations in mind it recommended a very small change to the existing codebase that did the same thing.

This is probably also the reason why most llm generated code stacks thousands of lines of code.