Sarpa Dosha/Naga Dosha in the chatt

Hello practitioners, i had a few question about Naga Dosha and Sarpa Dosha. Just to be clear, I'm not talking about the Kaala Sarpa Dosha(7 grahas placed between the rahu ketu axis). I'm talking about the one that requires ashlesha bali or sarpa samskara. How to you find out if a person has this in their chart? Prashna marga or the Cowrie Marga may give us answers but what are the indications from a chart?

From what I've seen, people say there are 4-5 different types of naga doshas based on the rahu ketu placement. That means around 70-80% of the charts have it.

Is it commercialised as they say it includes Rahu-Ketu in 1,2,4,5,7,8 houses? What's do the texts say?

What's the actual way of determining it?

It would also be helpful if you shared your experiences with people having such placements.

Thanks in advance!!