Agree completely Morsie.
The #1 thing is contrast, so at it’s simplest any 2 elements (line/background) with good constrast against each other will work.
We often can’t choose the line though, and have to work with what ever is on the rod. So setting up either through utilising angles or by asking your friend to cast at spot X is a step whereby we control or take advantage of a BG. Hense so much emphasis on choosing the BG thats going to make the line pop.
Backlit (into the light) are great for casting shots, providing its your BG elements (preferably trees or shrubs) thats backlit. It provides a nice siloette of the BG elements.
Both of these are ‘staged” or mock shots, that came about because I thought the BG and light would give me what I was looking for in both shots, so I had my friend high stick and the shoot an upstream cast.

