I'll add a little opinion for contemplation. First, I have all 3/16" lines and anywhere from 15-30 taps each. None of my laterals have optimum set ups as to fall and length. I only have two that have more than 10-15 feet of fall after the last tap. Most have 30 or more at the top, but as I get down slope I enter a more level area. I have never checked vacuum levels on these lines, but know I have some on all the taps. I run 5 of these laterals into a 1/2" main line once I'm out of the woods to my collection tank. I believe it still benefits me to run these 3/16th lines. I used to do buckets/bags on all these and going to tubing was an effort to reduce my labor after being diagnosed with heart disease and asthma. Here are my rationals for 3/16th tubing:

1.) Cheaper and easy to handle, set up

2.) Any vacuum is better than no vacuum

3.) Labor saving

I can go back over my records and show that even without optimum parameters I have gained sap, saved money and saved physical work with 3/16th. I think we get too hung up on perfection and max production set ups. We should evaluate what we want and if there is significant benefit in what we can do. Also, ask yourself, "do I need maximized sap production?". I am a hobby producer and if I pay my expenses and make a little extra money from sales, I'm good with that. If I can do it easier, I'm really good with that. Now if you have bigger operations and a high financial investment then I understand why you look to optimize every drop of sap, but from what I see there are a lot of producers on this forum that just don't meet that criteria. For them, if they can get some gain from a less than perfect set up then I say do it.