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So how do five ucl's make the slider come down quicker?

I wouldn't say that five UCLs make it come down quicker, because five is just a number. Its the distance between the outside and inside UCL that matters. The further out the outside most control line is, the quicker the slider might come down. I would think the line connected to the stabilizer would have more of an affect or atleast quicker than the UCLs. Since the UCLs are oreinted toward the back, they probably put a lot of force in the direction behind you. If that is the case all of the line should be relative to each other and there should be no difference between 4 or 5 UCLs.

This is only what I am visualizing:

1. Nose inflation
2. stabilizers fan out
3. Pressure begins on the front riser grommets
4. Full Expansion begins on the width of the canopy
5. Tail begins to fan out and puts pressure on the back grommets.

If the outside UCL is further out then I guess it apply force quicker, but I think the lines connected to the stabilizers should apply force first before the outside UCL.

This is just my thoughts as I'm procrastinating working on my Essay for Am. Literature. I recommend you wait to see what someone with more experience thinks.

What is a UCL?

Upper Control Lines, Apex BASE says the slider is slower with 4, and faster with 5. I've not seen every canopy made, but aren't most with 4 vs. 5, the difference is the 4th from the outside. In other words, isn't the most inside line of both canopies in the same place?

Is that for every canopy made? Just their canopies? Specific canopies?

I think that there are a lot more variables that go into slider deployment than just this one, and that having a 5th upper control line will potentially have a different effect on different canopies depending on line trim, placement of the 5th upper, size of the slider, etc.

The expansion of the tail and control lines are the biggest factor in driving the slider down. It's not clear to me that a fifth control line would add a statistically noticeable descent rate of the slide. I experimented with the size of the slider to improve descent rate years ago. The slightly smaller one gave a quicker opening but had poorer heading performance than a larger slider.

460: quicker opening but had poorer heading performance

There is always a trade off.

My wild guess is, the 5th control lines hold more of the tail down, catches more air so bottom skin expansion occurs quicker.

To help slow the openings, PD made the original Sabre 190 and up, with the most inboard control line separate from the rest. It was continuous. It was not set with the rest of the control line. It allowed more air to blow past the tail during deployment.