At later stages of development i use Gemini 2.5 Pro for brain storm sessions to formulate what I want and once I have it fleshed out, I ask it to summarize it into AI actionable prompt that is very detailed that I can copy and paste into a new chat session with any AI llm model that would have everything needed to implement what I want
Same I have paid subs with ChatGPT Plus, Claude Pro and Gemini Advanced and utilise them for brainstorming part without fear of token usage billshock as they are fixed monthly subscriptions.