Unlike the Roll Under on Multiple Dice, which test against the fixed score of the Ability in question (not knocking it at all), this method gives a fixed Target Number (and I provide both Roll High and Roll Low versions) based on the number of dice rolled.
Roll|---|Roll
Low |#d6|High
----|---|----
02- |1d6| 05+
----|---|----
04- |2d6| 10+
----|---|----
06- |3d6| 15+
----|---|----
08- |4d6| 20+
----|---|----
10- |5d6| 25+
----|---|----
12- |6d6| 30+
* 3d6 is still the 'Average' Task
* Level and Ability Score and other Mods ('+2 because you're a Ranger', etc.) could be added/subtracted from the roll, as appropriate for the method one were using.
* Contested rolls would still measure the degree by which each contestant succeeded, with less 'swing' the greater number (4d or more) of dice rolled.