What Eneka said is true. The benefits were quite different 30-40 years ago compare to now. My uncle (and aunt) are also able to fly First (when it was available) at least once a year when space permits. He was captain riding 74F. Kids were also able to fly free till they were 26.

With withdrawal of First Class now it's by a points system where if you fly long haul it takes more points and regional is less, more for Business and less for Economy. Typically you get to travel 3 times if you fly regional, and more if you are willing to take Economy.