That right there is why the 12" wide assembly you bought won't warp.... and every single board will. Those strips are glued up with the grain facing opposite direction from one strip to the next - which prevents warp, twist, etc.


(source)

Take a look at virtually every table top ever built - if it LOOKS like one big piece of wood, it is probably veneer laid over a substrate of either glued up strips (older tables, including VERY fine furniture) or a stable material like fiberboard/particle board/etc.

__________________
1961 220b: first project car - sold.
2000 CLK 430: first modern Benz - sold.
2001 CLK 55: OMG the torque!!! - sold
1972 280SE 4.5: Baby Gustav
1991 300TE 4Matic: Gretel the Snow Bunny - sold
1978 300SD: Katz the Free Man - given away
1980 Redhead: Darling Wife