A solid sawn column is held to an unbraced length of 50 times its least face in the NDS, so a 4x4 (3.5 in actual) tops out at 175 in and a 6x6 (5.5 in) at 275 in. The wall-framing takeoff now checks a stair landing's posts against that and warns when they are too long, saying what to change: a 6x6, or bracing.
It is a screening check from hand arithmetic, not an engineer's design: no buckling stress, bracing or stringer connections are modelled. Check against your code and the actual drawings.