Consider the sentence (which may in speech either be modulated to indicate an invitation to reply, signified here by the question mark, or not):
- "I wonder what he does all day long?"
The sentence sounds totally idiomatic. I don't really understand why the present simple is used here, if we use the present simple mainly for actions which are repeated after intervening periods of time (each month, week, year, etc). Can we also use it for situations etc lasting all day long ? We can imagine this as repeated actions occurring frequently all through yhe day?