Kalen:
Actually, when the TPC at Sawgrass was built, there was a big spectator mound on a peninsula sticking out into the lake between #16 and #17.
They took it out after about 5 years because you could only see one of the two holes at a time, and the people left of 16 green or 17 green couldn't see what was going on at the other hole ... in fact there were a lot of inopportune gallery-noise moments, i.e. a roar on 17 just as somebody was putting on 16. Nowadays, with the mound gone, the players on 16 wait to putt when someone is on 17 tee.