You'll see this is in the next playtest packet in a couple of weeks, which will include a standardization of difficulty values for attribute checks. In place of "a difficulty 15 INT check" or "an END check at difficulty 21" you'll see "a Challenging (16) INT check".
The current scale looks like this. Note that the descriptors are from the reference point of a normal human - what is impossible to a normal human might not, of course, be impossible to Einstein or James Bond.
[TABLE="class: outer_border, width: 500"] [TR] [TD="align: center"]Trivial
[/TD] [TD="align: center"]6
[/TD] [/TR] [TR] [TD="align: center"]Easy
[/TD] [TD="align: center"]10
[/TD] [/TR] [TR] [TD="align: center"]Standard
[/TD] [TD="align: center"]13
[/TD] [/TR] [TR] [TD="align: center"]Challenging
[/TD] [TD="align: center"]16
[/TD] [/TR] [TR] [TD="align: center"]Difficult
[/TD] [TD="align: center"]21
[/TD] [/TR] [TR] [TD="align: center"]Severe
[/TD] [TD="align: center"]25
[/TD] [/TR] [TR] [TD="align: center"]Impossible
[/TD] [TD="align: center"]29
[/TD] [/TR] [/TABLE]
You'll note, from the above, that shooting at somebody's DEFENCE score is typically a Challenging -> Severe AGI check. In other words, it's actually quite difficult to hit someone. That's where the aiming, pinning down, crossfire, suppressive fire, etc. come in. The combat becomes more mobile as position makes a big difference - it becomes almost a chess game as each side jockeys for position to get those AGI checks down to less difficult values without sacrificing their own DEFENCE.
The current scale looks like this. Note that the descriptors are from the reference point of a normal human - what is impossible to a normal human might not, of course, be impossible to Einstein or James Bond.
[TABLE="class: outer_border, width: 500"] [TR] [TD="align: center"]Trivial
[/TD] [TD="align: center"]6
[/TD] [/TR] [TR] [TD="align: center"]Easy
[/TD] [TD="align: center"]10
[/TD] [/TR] [TR] [TD="align: center"]Standard
[/TD] [TD="align: center"]13
[/TD] [/TR] [TR] [TD="align: center"]Challenging
[/TD] [TD="align: center"]16
[/TD] [/TR] [TR] [TD="align: center"]Difficult
[/TD] [TD="align: center"]21
[/TD] [/TR] [TR] [TD="align: center"]Severe
[/TD] [TD="align: center"]25
[/TD] [/TR] [TR] [TD="align: center"]Impossible
[/TD] [TD="align: center"]29
[/TD] [/TR] [/TABLE]
You'll note, from the above, that shooting at somebody's DEFENCE score is typically a Challenging -> Severe AGI check. In other words, it's actually quite difficult to hit someone. That's where the aiming, pinning down, crossfire, suppressive fire, etc. come in. The combat becomes more mobile as position makes a big difference - it becomes almost a chess game as each side jockeys for position to get those AGI checks down to less difficult values without sacrificing their own DEFENCE.