"Waterfall out 90 days" is not what is derided as Waterfall. The derided form of Waterfall is for large applications and commitments, 90 days is small in context. That's the prototype phase of a project that Waterfall may be applied to.

The basic model of Waterfall is, indeed, fine if you iterate, which then isn't Waterfall. The basic model + iteration + shorter timeframes (probably under 90 days, certainly under 180) is basically just the same plan-do-check-act cycle from Deming (and others). You want it to be shorter so you can respond to new information (including the results of the partially developed system). Waterfall, the derided form, doesn't give you feedback until final delivery, or maybe the phase called "FQT" (final qualification testing). Importantly, until the customer is re-involved (which may happen in FQT or in delivery) you don't get revalidation of the system.

System engineers learned and applied this as far back as the 1950s, at least. No serious large scale system uses Waterfall and reliably succeeds.

You’re basically describing Scaled Agile. They have big planning meetings every 8-12 weeks (called PI Planning) where devs make a plan based on priorities, work out dependencies and get agreement with the business side of the house about the plan itself.

In my opinion, it’s the ideal balance of concerns.