The Use Even Stepdowns option controls how the stepdowns are distributed.
The Use Even Stepdowns option.
Enable this setting to force even stepdowns. By default, the maximum stepdown is used to ensure as much as possible of the flute is used. However, this means that the last steps are adjusted to fit the machining depths and hence result in uneven stepdowns.
Stepdown 4mm, total depth 10mm
Left: Use Even Stepdowns disabled.
Right: Use Even Stepdowns enabled.