I'll fan the fire with my opinion/ observations. You do need tree gas or air to make a star ladder work. If your system is tight to perfection, no hollow trees, etc, the laddder fills with sap and the vac level past the ladder drops. I put in a new line with 40 taps going into a 12' high star ladder with 4 vertical tubes. I watched it fill and only occassionally move. I said to my self I wonder whats going on, do I need a leak or is it just feel good watching the sap go? I installed a vac gauge beyond the ladder. When the ladder was full I had 22" at the releaser and 12" past the ladder. Every time the ladder would rip and empty the vac past the ladder would go up to 18", then the lines would fill and vac would slowly go back down to 12". So, I intalled an extra saddle with a piece of 5/16 with a needle valve on the end. I fine tuned a tiny leak, allowing the ladder to work and vac past the ladder stayed at 18" or above ALL THE TIME. Yes leaks are bad, but I'd rather have a leak and 18"+ than no leak and 12". In most situation there will be enough tree gas or existing leaks to work fine, but I believe that my observations show that there will be rare intstances where an introduced leak will be beneficial.