I've been asked this question in a forum message and it comes up as a criticism of GUMSHOE fairly frequently so I thought I'd post here with my response. Can it possibly be a sticky thread, because it's basically dismantling a misunderstanding those who are weaned on d100 have when trying to grok GUMSHOE and everytime I see it thrown out there I have a Cookie Monster meltdown.
One thought I had today about ToC is its core mechanic doesn't make ANY difference between an amateur and a professional. Absolutely no difference.
A professor who spent 30 years studying Egyptian language (4 points in Language - Egyptian) and a student who spent only several months (1 point) will equally translate the manuscript according to the rules. And even if they both spend 1 point of Languages they still get the same result.
A rookie GI on a shooting range is as effective at hitting the target as a grizzled veteran who spent 5 years fighting in different conflict zones.
You may say that the veteran and professor have more points to spend - that's right, in an instant action they have advantage. But in the long run?
After a veteran spends all his points for the first shots - he becomes the same as a rookie, no more advantages at all!
While in other d100 systems a veteran with, say, 70% Shooting skill ALWAYS has more chances of hitting a target than a 25% rookie.
Example 1 - Investigative Ability Spends:
Academics: Fred, an undergraduate, has 1 point in Languages - Egyptian. Brian, a professor, has 3 points in Languages - Egyptian.
If you have a situation in GUMSHOE where there are "levels" of information to be obtained from a clue e.g. what a professor would glean versus what an undergraduate would, then that clue has multiple point spends. Using an example of the investigators studying an ancient papyrus:
Spend 1 point - you find out the Egyptian pharaoh's name on the papyrus was Amhotep
Spend a further point - you find out his queen was Clapetrah
Spend a further point - you find out Amhotep is another name for Nyarlathotep
( that is some hefty point spending vs. reward but I'm just throwing a quick example out there to illustrate the mechanic )
Fred, the undergrad, only has 1 point to spend so only gets the first clue.
Brian, the professor, has 3 points, so gets 1, 2 or 3 clues depending on how much he wants to spend.
Or, an alternate method is that the scroll is complex to translate and needs 2 points to be spent on it to get all three clues. Fred only has 1 point because he's an undergrad so he can't spend enough and he can't translate the scroll. Brian is a professor with 3 points so he can spend 2 points and gets all the clues.
If the papyrus only required 1 point to be spent to get all the clues then, yes, Fred and Brian are no different from each other, but that would be no different in CoC either - Fred might get the clue or Brian might get the clue depending on how they make their %rolls. Fred might make his roll but Brian might fail his, which means an undergrad translated the scroll and the professor could not! Or even worse - they both fail which is a rubbish outcome - what is the point of putting a clue in the scenario if a stupid dice roll means no one gets the clue ?
Finally, Investigative points are also to be spent for Benefits. So Brian could show off 3 times creating 3 Benefits for himself whereas Fred could show off only once with his 1 point. Which is pretty much how a professor vs. undergrad should work.
Example 2 - General Ability Spends:
Shooting: Fred, a war veteran, has 8 points in Firearms. Brian, who's done a bit of hunting, has 2 points in Firearms
General Ability points are there for when you really, really want to succeed so I'd say your shooting gallery example is not a great example because there is nothing at stake. So let's say the loser of the shooting gallery contest is going to be executed!
Fred has way more points to spend than Brian so in a Firearms Contest ( by "contest" I mean a GUMSHOE Contest as defined in the rules ) Fred is way more likely to win because he can spend more points each round and is less likely to fail than Brian.
If we move away from a single critical example and talk about an entire adventure then Fred has more points to spend than Brian over the whole adventure and therefore probability means he will be successful on more of his test rolls than Brian, thus showing his superiority in handling guns throughout the whole session.
If you are just isolating one point in time where Fred has the same remaining points as Brian then you need to ask "Why does he have the same remaining points as Brian ?" It must be because he's already been spending points during the adventure thus showing off how great he is at guns, whereas Brian mustn't have been spending points so he's either not been firing at anything ( because he's not as good as Fred who's been defending the party all the time upto now thus showing how much cooler than Brian he is ) or because he's been saving his points, in which case his probability of hitting has been less than Fred's chances ( again showing how much better Fred is at shooting than Brian ).
If a character were to walk upto Fred and Brian and just ask the question "Who's better at shooting ?" then you look at the investigators' rating not their current pool points. So Brian would have to say "Fred is best".
So the difference between d100 systems and GUMSHOE is that with a d100 game ( e.g. CoC ) the difference in skill % in an ability for two characters evidences itself at the same rate across the entire session ( e.g. in CoC Fred has Handgun 70% and Brian has Handgun 20%; probability-wise Fred is 50% better at every point in the adventure ). Whereas in GUMSHOE the player gets to choose when he wants to be better/increase his chances of success ( by choosing when to spend points on General tests or Investigative spends ) but overall he will be better across the entire session as well ( just not at a uniform rate - he will have several peaks of "being better" and several times of being "just as good" which average out at "being better overall" ).