Drag is good. It allows you to save your acceleration/rotation for when it really matters ie late in the stroke. Also fits best with how we like to throw things. It’s the basis behind distance casts, and also roll casting.
Now where the definitions models clash, is that here at SL, Drag is part of the Stroke. It’s already begun. We are moving the line, we are getting it moving in the direction we want to send it. IFF have defined it outside the Casting Stroke, which is not very helpful.
But if you ignore all of that, modifying a casting stroke to include Drag allows us to delay rotation. That is the essence of distance casting. “Lead with the rod butt”.
For me it’s an intermediate/advanced level thing. I would probably introduce it (briefly) when teaching roll casts. But I really get into it with advanced distance. When teaching distance I often teach Drag using the Dynamic Roll to learn it - it slows things down and you don’t have to deal with the backcast falling or timing etc. (Not over grass anyway!)
I’ll draw some art tomorrow. Swinging around in my hammock at the moment so this is not currently possible
Cheers, Paul
), I have a bit more time TO practice. 
