After a little research on why Martin Short is part of the “5 Timers Club”, even though he has hosted the show 3 times, the reason Martin is a part of the club ’cause he was a regular cast member from 1984 – 1985. The year 1985 has the number 5, therefor, that’s what makes him qualified for the, “5 Timers Club”. Anything that has to do with 5, makes an SNL star eligible. I thought this was interesting, so I thought I would share it. Now I understand why he was a part of that group shot photo.
Edit to add: Same thing with Dan Aykroyd, he hasn’t hosted SNL that much, he was regular cast member from 1975-1979.
Kev
K'Brocking 
It’s actually just a running joke, dude. Started with a skit Tom Hanks did about it in 1990.
It may have been a joke at first, but seems they have turned it into a real thing. On top of that, SNL isn’t relevant anymore. They used to be great when Chris Farley and Adam Sandler used to be around, but SNL is crap, right now.
Kev