I'll assume for a second that stats will continue to be +1 for a 12 and +5 for a 20:
Untrained in your worst stat? -1 skill check (8 strength)
Untrained in your best stat? +4 skill check (18 strength)
A five (5) point span is a 25 percentage point gap on a 1d20 roll. Training is going to make those gaps even worse. Skill focus is going to make those gaps extreme. (Therefore I would argue that +1 stat bonus per 2 pips is WAY TOO MUCH. Ok, done with that rant.)
Trained in your best stat? +6 skill check
Shooting for 70% success rates on a trained specialist (using your best stat) you get a DC of 13 for that +6 skill check (you succeed on a 7 or better).
Trained with skill focus in your best stat? +8 skill check and an 80% chance of success.
Problems occur if you raise the Trained bonus to +5. That DC 13 needs to get bumped to DC 16 and unskilled attempts now face an abysmal 20%-30% chance of success which means DON'T EVEN ATTEMPT THIS. Making skill rolls reasonably impossible for those who don't have the perfect alignment of stat bonus and skill training is bad for the game. Magic becomes required to get through relatively normal terrain or situations because magic negates the need to have the right stats/training.
Untrained in your worst stat? -1 skill check (8 strength)
Untrained in your best stat? +4 skill check (18 strength)
A five (5) point span is a 25 percentage point gap on a 1d20 roll. Training is going to make those gaps even worse. Skill focus is going to make those gaps extreme. (Therefore I would argue that +1 stat bonus per 2 pips is WAY TOO MUCH. Ok, done with that rant.)
Trained in your best stat? +6 skill check
Shooting for 70% success rates on a trained specialist (using your best stat) you get a DC of 13 for that +6 skill check (you succeed on a 7 or better).
Trained with skill focus in your best stat? +8 skill check and an 80% chance of success.
Problems occur if you raise the Trained bonus to +5. That DC 13 needs to get bumped to DC 16 and unskilled attempts now face an abysmal 20%-30% chance of success which means DON'T EVEN ATTEMPT THIS. Making skill rolls reasonably impossible for those who don't have the perfect alignment of stat bonus and skill training is bad for the game. Magic becomes required to get through relatively normal terrain or situations because magic negates the need to have the right stats/training.
