Looking at Btn vs BB flat in pio and am trying to get a better grasp of when to cbet big (66%) vs small (33%) on high card boards. I'm using a BB strat that 3bets 99+/AK, AJx/AJo (75%), AQo (75%), AQx (90%), KQx/KQo (75%), Bdwys/SCs/A2x-A5x (25% each).

Majority 66% sizing: Ad Js Ts; AcKhJd; As Kd Qs; KcJcTh (40% big/25% small)
Majority 33% sizing: Ks Qd Ts (40% small/20% big); KdQsTs; KcQhJd

It seems that the K high boards have a tendency to use the small sizing vs the A high boards. Can anyone help articulate as to why this is the case?

To illustrate range breakdown of a big size and small size example:
AcKhJd IP 52.3% EQ, bets 2/3 52% and 1/3 3% -- Strt (3.3%), Set (1.8%), 2pr (5.5%), top pr ( 22.6%)
OOP Strt (3.4%), Set (0%), 2pr (3.3%), Top pr (24.1%

KcQhJd IP 52.5% EQ, bets 2/3 10% and 1/3 41% -- Strt (6.3%), Set (1.8%), 2pr (5.3%), top pr (13.5%)
OOP Strt (6.8%), Set (0%), 2pr (5%), Top pr (11.3%)