I think practice for the sake of safety is a good enough reason. Our ability to rig can vary based on circumstances. Picking an anchor can take longer than a minute, and can have a significant impact on how well the one minute rig works. I practice to remember how to do it correctly more so I don't screw up when it counts. It is so difficult to slow down and assess a situation. I've seen viral rescue videos and people easily spot the mistakes that are made. I think many times people get tunnel vision and don't slow down to make the best decisions. Some of those times people just aren't well practiced. We want to rush and be as fast as possible.
Come to think of it, I have never thought about scouting a rapid for pins and potential actor points. I should probably start now that I am rafting more and kayaking less. I love to be in a position to help out, even when it is another group. I'll have to start looking at rapids differently.
Wishing I was on the river instead of surfing the web...