I don't quite get this "hour building" stuff.
For the FAA ATPL you need 1500hrs TT of which 100hrs must be at night. That is a huge number of hours to log. Flying to exhaustion, say 3hrs/day 6 days/week it would take 83 days to accumulate that. Does anybody really do that??
For the JAA ATPL you need the same but 500hrs in a multi crew cockpit, which is totally beyond any private individual to do in a sim or in a real MC plane (unless you are a multi multi millionaire). This is why ATPL cadets do the CPL/IR and then look for an airline job ASAP. They cannot actually fly anything (safely) let alone a 737 with passengers, but the airline puts an old experienced ATP in the LH seat. These people don't need to hour build; it doesn't make sense.
What am I missing?
On a different tack, I bet a ton of logbook forgery goes on in this game.