Just the first three seasons, Borneo on Wednesdays and Australian Outback/Africa on Thursdays. That's it. By the time Africa aired, the show had lost nearly ten million viewers and was no longer the #1 program on television, hence more reason than ever for Survivor to pre-empt the lower rated Sunday slot rather than CSI which was becoming CBS' #1 show. Survivor: Africa ended up having a late start and finishing early the next year, so they kept the finale in the regular timeslot since it wasn't going to be airing against much competition or pushing out higher rated CBS shows. By Marquesas, CSI was #1, I believe, and from there they've done Sunday finales ever since. It was also the first (and only) finale I missed and didn't see until years later since we had one television and my dad insisted on watching the X-Files final episode.
I think Survivor now is higher rated than the rest of the Wednesday night lineup in the key demo, hence why they can air it in that slot. Of course, all they ever had to do in the past was simply program the Survivor finale to air a week after the rest of the Wednesday/Thursday line-up has its season finales...then they could have aired the three hour thing in place of what would normally be reruns and with no real competition...but whatever.