Better to be overly critical then to assume the best. A case in point my home table. Which sits on an engineered hard floor floating on concret. That table was left in place for weeks before being leveled over the course of days using a combination of a theodolite and of course machinist levels. Slates were brought true to one another using ~>1" wide shims, (6 per slate section). Over the course of a year or two the shims 'settled' into the frame and slight drifts appeared.Don't overanalyze.
If you set any table up well on a stable floor and environment, it stays level.
Were the drifts 'bad'...?..., well that's a matter of perspective. Was it on a stable floor / environment, but manage to come out of level...?..., definitely yes.
Next time around I'll be using jacking screws in the appropriate locations, and float the slate.