The difficulty comes when the limit of duty time seems like it is the target and getting as close to it as possible on a regular basis is a measure of crew planning effectiveness. I vividly remember an overnight to the middle east and back to Scandinavia followed by minimum rest during the day in an airport hotel and another overnight to the middle east arriving back at home base at six in the morning. I had a frustrating chat with management who just kept repeating that it was legal. A couple of months later sanity prevailed and it got changed to a 46 hour very pleasant stopover.