In general though, friction is your enemy. You can counter-act a little extra weight with more rubber bands, but friction is never good.
Symmetry is very important, not just weight left-right, but also the length of the bars. If you have a longer bars it can cause the geometry of the lift to change as it moves, making the lift “non-linear.” An ideal dr4b has all 4 bars identical lengths. Changing the top 2 to be shorter or longer than the bottom 2 will cause the lift to “drift” forward or backward as it goes up. Longer top means forward, shorter pulls backward.
Another issue to watch is wobble. Now this seems like tightening the joints would make it wobble less, and it does, but it also make the lift get “stuck” leaning, which then get worse the more it tries to fix it. So by making the joints looser, the lift can fix itself easier, which overall decreases wobble. And cross bracing is important, of course, but not always easy to do if the middle of the lift has to be open.
Those are the 3 biggest things to watch IMO. Hope it helps.