Generate And Test Algorithm - How to structure & datafy test ?

Something a bit off-topic, but still close to OM workflow.

In the book „Fundamentals of Composition with Opusmodus“ (1st book) the authors introduce the GAT algorithm.

GAT stands for Generate-And-Test.

Developing code myself in my day job as Data-Scientist, the testing approach resonates very much in me in general.

The majority of posts in this community forum deal with the Generate-part.

In contrast to Data-Science, the Test-part in music to my understanding is very subjective and depends on intentions. So thats OK, But:

My personal expereince is that once I hear a probalistically generated piece I loose the ability over time to test in a consistent way.

I wish there would be a way that my test is structured, stored and ready for comparision, say a day later.

Also I wish that this test may be integrated in code for a fast rinse-reapeat cycle.

Still I ask myself whether there‘s a disciplined semi-quantitative approach, without giving up the creative flow an acceptance for personal preferences etc..

Any Best-Practice or other experience from the musicians and composers?

[Edit: No worries - I am not implicitely targeting with my question toward reinforcement learning.]