So with table legs, even though measurements are carefully done as well as the cutting, once they are screwed on the the table they are uneven. Am thinking tightening the screws is throwing it off. Any tips?

Check to make sure your table top is not warped. Apron or no apron? And post pics.

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if they are on an angle, pick one and make a gauge to match the angle, match other legs up to the angle.
if it is a tiny amount and concrete floor, move it around some to see if they even out, slab could have some minor dips.

use a battery drill and set the clutch to about 5-6 to start, redo all screws till it ratchets, increase if needed for tightness.

Get some of those small stick-on felt pads for the legs. You may be able to make things even with that. And I could send you some stick-on felt if a thinner pad is the possible answer for one or more legs.