I think this is a good hallmark of the difference between early Sierra games and early Lucasarts games, Sierra had some illogical puzzles that could lead you to dead ends, whereas Lucasarts games always seemed to make sense logically (also the lack of failure states was nice, bar the easter egg in MI1).
QFG4's install time was huge, but then it also had full voice work for narration, so I'll give it that. QfG2 is by far my favourite of the series, though.