When it comes to weather we are taught a hodge-podge of methods
I am in the final throes of renewing my lapsed IMC (IRR) rating
I don't have your experience but I share your methodical approach
When it comes to weather, my current IMC instructor is a great source of experienced wisdom, to wit ...
If cloud cover at destination = broken @ circuit height, then chance of successful arrival < 50% = 'Do you think you're lucky??'
SD