halacha - Is there such a thing as an on/off וסת?

Coming off the recent question of complex וסתות, what about a pattern of 27,29,30; 28,29,27; 31,29,30?

In this case there is a pattern for every middle one while the rest remain random. Are we קובע a חזקה interspersed with non-מוחזק data?

On the one hand we can equate this to the ox that gores every third person. In that case the people he skips would usually tell us that he doesn't gore, but we look past that and count the pattern. Here too, ignore the random and count the pattern.

On the other hand, in the case of the ox we have a quantified pattern, and here we don't. Any sources or solid arguments are appreciated.