It depends on case. If patient is anaible to understand correctly the scheduled procedures, surgery, etc. or he/she needs a relative to come to final decision, but sometimes a patient asks not to tell everything to somebody ... to keep medical secret
I uphold the phenomenological theory (from which I derive my book: narrative nursing ) that defines that person and the family are a single unit, so I support the presence of the family in every department, even in intensive care
For company the visitor should stay as long as he/she can, but not actually live in the hospital. It is a bit of interference to be there all the time, the health people need to do their work.