The help of the co-sponsor is not sufficiently valued.
I would not be here if it was not for my co-sponsor.
My first sponsor was missing. He did not contact me a single time. After a few months he opted out.
All the help I needed came from my co-sponsor.
My advice to co-sponsors is to treat their CSAs as if they were PSAs. If they don´t need the help they will not take any notice, but many may need it.