Low strength training

I remove them before the stems outgrow the benders... by that time the stem has become rigid (there's a technical term for the process, but i can't recall). No reason to damage the vascular tissue as the stems grow thicker than the plastic allows. As long as the stems have become rigid, they won't change much after that... they can lurch upward but will never correct the bend in a significant way. The bend doesn't restrict anything, but plastic cutting into the stem can -- xylem is just as important as phloem and unnecessary damage is wasted resources healing it. Based on the picture shown, those stems will definitely outgrow the plastic benders at some point.. when they start to feel tight and don't jiggle, take them off. A little scratch is nothing to worry about.

The clips have absolute zero effect on "nutrient flow", so you can safely leave them in place for the entire grow. Nutrients are transport up and down the plant via the phloem, which is located deep inside the stems, so the clips on the outside of the stems do not affect nutrient transport.

Started using these and there good at what they do, opens up a load of light down to the lower nodes, don't leave on through flowering, remove once the clip has done it's job

I always found them to be more hassle than they were worth, causing more damage than was necessary. What little usefulness they had can easily be replicated with much easier tools to get the job done. Maybe I'm just clumsy. Laminar flow itself is not always most efficent for nutrient uptake, turbulence created from corners and bends adds resitance that supports better nutrient mixing and absorbtion. Gluck.

chances are, your plant will gladly bust these apart if you did forget one, but you should remove them accordingly. idk. maybe you have a REALLY nicely printed set but the plant should have no issue destroying this as a side effect of growth the setting only takes a day or two IME with these same 3D printed clips

LST= Low Stress Training not Strength 😉

can remove em if you want, can also leave em. They don't impede the flow of nutrients "or if they do its such a small amount I would not even think about it" they only alter how the branch is set/formed. Now if the branch is outgrowing the size of the elbow, then its time to remove it. as its shrinking its diameter and putting pressure on it. The plant will adapt but best to remove at that point.