The cable areas in the clips for 1.0 inch diameter tubing are designed to hold 8 typical “SVT” power cords (UL-Type SVT, 3C/18AWG 300V, ~6mm in diameter), as shown here.
The area available on the 0.25 clips, that fit over the shelf racks, is about 6-7 SVT cords, while the 0.25 Large Capacity clips can easily hold 10-12 SVT cords. The Large Capacity clips are more intended for tubes you might find in a hydroponic or laboratory setup.
“Well yeah, but my cables are HEAVY!” The thing to remember is that no component is ever infinitely strong, nor will anything (besides time itself) last forever. The same is true with 4CELNK-YR clips. There is some large amount of force that will break them. I haven’t reached it yet, but it’s not at all impossible to yank on a cable and pull it out of the clip. (If you’re going to be violently pulling the cables, then maybe stick with tie-wraps)
If after all that you still need more capacity, consider adding more than one clip, and arranging them around the tube circumference to provide multiple wiring “channels, as in the photo at right.”
From what I’ve been able to tell, “a couple pounds” (~1kg) is just fine as far as holding strength. I might be inclined to add more bands (5-6 instead of 3-4) up to about 5 pounds (2.2 kg), but beyond that weight you should consider adding more clips.