With all the details these guys have to report, it's a wonder they aren't all in jail. So many of them are involved in lobbying and other activities on behalf of foreign governments and the travel....holy shit. But they KNOW it's coming; they have to file this paperwork all the time. So anyone with half an organizational brain cell would keep a running list of where they had been and with/for whom, so they could spit out a detailed report whenever they are required to do so.
I feel bad for anyone who is trying to report this kind of stuff for the first time. I can't remember where I had lunch yesterday. Easy to forget stuff, for real.