Plus on achète, plus on vend, plus on règle de problèmes, et plus notre cité sera florissante !
I just came across this colloquial sentence that deviates from the usual "plus ..., plus ..." construction. Here, the three-tiered "plus"s as a whole make up the first {cause} part, and the "et plus" forms the second {effect} part.
The way the four "plus"s are connected stands in stark contrast to how it works with the equivalent English construction where "and" is used to connect the 2nd and the 3rd "plus"s.
I think that the cause/effect break is between the 3rd and the 4th clauses, especially given how the present tense is consistently used for the first three clauses ("achète", "vend", "règle") while only the 4th clause has the future tense "sera".
If I'm on the right track with my assumptions, I wonder if this is really how French speakers commonly arrange this multi-layered construction?