I understand where you're coming from, but I look at it this way:
In combat, you will consistently make use of the timing die, but you also read the face value, so your 7-Result problem doesn't come into play.
In other circumstances, why even bother with a timing die at all, unless the situation is time critical? At most, you'll take the high die as Effect, and, as GM, maybe make a brief comment about how long it takes based on how high the Timing die is (no maths required).
When Timing really matters, then picking Timing and Effect dice can be an important player tool. Single digit subtraction shouldn't be an issue in these relatively rare, but important circumstances.