To avoid having to do "+s" and "-s" with negative numbers would the following revision to the IRC and Key Count make sense:
2 decks - Revise IRC to 5 and Key Count to 10
6 decks - Revise IRC to 24 and Key Count to 40
8 decks - Revise IRC to 28 and Key Count to 50
You can revise the KO numbers in the manner you suggest as long as you adjust the index numbers accordingly.
1) Due to the upward pressure on the running count, it is unlikely to drop by 20 or more.
2) If the count falls too far, you should not be playing anyway.
3) It requires more effort to count twenty-something and thirty-something than anything from zero to nineteen.
I've always used IRC=0 for any number of decks. Not much time is spent in negative counts as the count either recovers to positive or you reach an exit point.
If I were starting over I might start with IRC=10 and hardly ever see a negative.
In either case you have to adjust your other numbers depending on the number of decks.
