A lot of trading is indeed done by minimally supervised computers, i.e. a human only looks at the computer if alarm bells ring. Source: was one of those humans
The pipeline for a given piece of research to get into production tends to be several months. Therefore, a small firm with only a few researchers might update between once and a few times a month, and a larger company it might be several times a week. It's rare to update the model more than once a day, since it'll normally be updated outside trading hours.
