Consider a rocket with two or more motors; symmetrical thrust is that which you find in most flight operations since an equal amount o' thrust is provided by all motors, shiver me timbers, unless an motor fails [to ignite] or has a different thrust than t' other(s). Safe operation o' rockets with different motor thrusts, in a cluster would be t' ensure symetrical thrust around t' center vertical axis o' t' rocket. See also Vectored Thrust