I was in Switzerland using my flexipass, being a good little tourist and entering each date as I used it. There was a section below where you could log your actual trips, I'm a semi-train geek but didn't feel the need to go into THAT much detail. After several uneventful rides my luck turned on the Golden Pass, when the conductor very sternly told me that I had to fill in ALL the train trips I took. To me that's like keeping track at a buffet, but then he told me the real reason - it's not for us, at the end of the trip you're supposed to seal up your pass and send it back to Railpass HQ in Europe. They tally up all the trips that tourists took and, inferring what the guy was saying, give each rail company a payment based on same. To help keep the lights on and the trains running.
So even though the appeal of a pass is its AYCE nature, help out the trains in Europe and fill out that list and then mail it back after your trip. There's a box you can check asking them to return your pass when they're done.