Vyxal r, 6 bytes
T%UL⁰>
Port of Jelly answer.
How?
T%UL⁰>
T # Truthy (water) indices of the (implicit) first input
% # Modulo each by the (implicit) second input (the stride)
U # Uniquify
L # Length
⁰> # Is the second input (the stride) greater than this?