I store mine on it’s side in a deck box when not in use which is mostly just over the winter unless we’re having company & I want it out of the way.
During the pool season it stays in the pool most all the time aside from when I take it out to clean it’s basket/filter, rinse it off, & loop up it’s cord as it runs on a daily schedule for me.
There’s been some reference to cold water temps allowing for water intrusion to places it shouldn’t get because of gasket shrinkage. This is mainly an issue for those who leave their pool open year round. The coldest water my bot ever swims in is about 60 degrees. YMMV.
The sideways, upside down, or on blocks thing (which is what a caddy provides) is to prevent the brush(es) & tracks from getting mashed down.
The controller box is not weatherproof, it’s only weather resistant & should always be kept out of the rain/sun. Mine is mounted inside my deck box for this reason. High temps & uv are very hard on electronics.