In my not very humble at all opinion I find the 3 clue rule is just an attempt to apply a band aid over the problem that GUMSHOE eliminates entirely.
The problem is that PCs can miss clues through not fault of their own. The three clue rule simply throws in enough clues that the PCs would have to be very unlucky to miss them all. Gumshoe ensures that the PCs never miss vital clues because Gumshoe contends that finding clues isn't the fun part of an investigation - interpreting them is the fun bit.
The problem is that PCs can miss clues through not fault of their own. The three clue rule simply throws in enough clues that the PCs would have to be very unlucky to miss them all. Gumshoe ensures that the PCs never miss vital clues because Gumshoe contends that finding clues isn't the fun part of an investigation - interpreting them is the fun bit.