When we make patterns we cut em fast and loose. Once its roughly even almost close fill in the gaps with strips of paper and tape. Then trace the rough pattern on a clean sheat cut it out nice and fine tune it again with paper and tape.
At this point you'll have a perfect pattern.
So yeah, rough patterns dont phase me. They just that a rough draft, good enough for seeing an idea or saying nope, that dont work.
We go through a LOT of poster board. We buy it it by weight not by the sheet...
Keep going, nothing is cooler than something you pull out of the air and see it become real.