Basement walls not 16 or 24 inch centres

I'm planning on finishing my basement this year. Walls are already framed insulated and vapor barrier is up. Problem is none of the framing has been done with a 16 or 24 inch center. Spacing seems completely random. What are my options in this case. Do I have to move boards to correct the spacing or add boards in? Do I just cut all my drywall to match the spacing as best I can?

thanks for any help