When is an idea worthy enough to reach out to a target audience?

Merhaba

So, I embarked on my journey of making money and at the moment I learn, learn, learn, ...

Now, I have some ideas which feed through initial questions to filter out ideas that are worth exploring (it is a 10-minute test). Let's say, I have 20 ideas and of these 20 ideas, maybe 1 or 2 seem to be interesting and worth exploring further.

So I have 1-2 good ideas. For this kind of idea, I normally start to write a (lean) business plan. A business plan helps me to shed the light on new viewing points that require examination or learning.

The most recent point I got stuck and invested time in was the target audience. I get the value and why it is important to talk to the target audience before even thinking about the product/service.

Now, that's all cool and fine. Out of this constellation rises a question:

What are metrics that I can use to verify that my idea is worth going through the work of conducting target audience interviews?

The reason why I ask this question is, that the effort to conduct interviews can be heavy and I only want to do that if other metrics of the idea highlight a worthy idea.

For example, to verify if it is worth writing a lean business plan for an idea, I ask myself appr. 10 questions about that idea. I give each answer a score and the total score determines if it is worth it for me to do the writing. Are there similar key metrics that you use before going into interviews?