I was under contract with my belgian company and sent to the offices of our Japanese counterpart in the context of a joint-venture kind of thing. Since I was under belgian contract, I had 'regular' belgian office hours (9-17, 5 days a week). However, once you're there you automatically get sucked into the local working hours and mostly I worked a lot more than the 'official' hours. It wasn't unusual to work like from 6:30 till 23:00 on weekdays and sometimes do some teleworking at my appartment on Saturdays. On the other hand, I did have regular 'dead moments' at the office in the middle of the day, during which time I could catch up on my private mails and stuff like that.
In average, I think I easily worked about 70 hours a week.
Sorry for the thread hijack m(_ _)m