in and out
1. Thoroughly; down to the last detail. I've been studying this material for weeks now, so I know it in and out.
2. Alternating between being at or in a location and being gone from it. The boss has been in and out of the office all day.
ˌin and ˈout (of something)
going regularly to a place: I’ve been in and out of the travel agency all this week, trying to arrange my holiday.After the accident, he was in and out of hospital for a couple of years.