For a western-europe work ethics, how many hours you're expected to be productive in a full-time IT job?
I'm always in the office 10-15 minutes before my official starting time and I leave the office 10-15 minutes after I'm supposed to. However, due to the flexible schedule (meaning other colleagues arrive between 8 and 9) I'm actually not productive for the first 30-40 minutes in the office. If you count in few coffee-breaks I can confidently say that I'm effectively working 7h/day. Of course, if there are deadlines or urgent tasks, I get them done ASAP but it's not the daily routine.
Where I work this is perfectly acceptable but I was wondering if that's the widespread behaviour.
EDIT
Even if the question might be opinion-based there are methods used to quantify the number of actual working hours vs total working hours (as I learned from OECD link in the accepted answer).