No idea on how long it took to clear trash to get to bosses, but as far as actual boss fights went, I don't think any actual single attempts took anywhere near that long. But if you want to look at what might be the closest to an EQ "equivalent" of PW, this is a good start:
http://www.fohguild.org/forums/mmorp...wrong-you.html
Also, EQ had *tons* more targets to raid, everything (or practically) everything was world spawn for the first 4-5 expansions, and there was no limit to the # of people you could have fighting something at once.