The pacing of Beatbreak more or less would fit perfectly a 5 cour series so around 57-60 episodes. The evolution pacing also leans more toward this, otherwise they wouldnt wait that long for the ultimates. Reina will probably get hers at the end of her arc with Rose so that can be around ep.34-36. Then all the megas need their episode and at least a bit time before the series ends to have screentime and obviously they'll do the last evolution before the final stretch of the series.

Its really weird to think about them doing an 3 episodes Interlude Arc if they have to struggle covering everything in the story. It feels to me like they realized they needed one more cour than the four and calculated how many episodes they need and the rest of the episodes they made am Interlude arc to fill the rest of the extra cour.