What is the timing consistintcy cake to cake

[glfrjerry]

I have been doing annual July 4th shows for a number of years using fusing. I watch/download Youtube videos to see effects and get time duration of cakes. My experience leads me to believe there is a substantial variation from cake to cake of the same cake. The videos of longer duration cakes vary by 10-20 sec. For example one video of "Bent Rail" shows an activity duration of 70 sec and another shows 90 sec. Is this much variation common?
I test each batch of fuse to establish the burn rate so I think that is not a problem.
I am most annoyed when I try to have 3 or 4 of the same cakes finish together and one runs longer and ruins (for me) the effect. Any advice will be greatly appreciated.

[Stormcrow]

I have similar experience. I feel like fuse past a foot or two varies as well. I found the SO76 proline to be far more consistent vs phantom, winda, brothers, and cannon.
I really feel like you can’t have predictable timing with consumer fuse which is why I went to cobra.

[displayfireworks1]

This is why professional companies do not use Consumer Fireworks in displays. There is no consistency and accuracy the majority of the time as far as choreographed timing. This is where pro-line products and/or Articles of Pyrotechnics are used

[Kenny East]

Consumer fuse varies from foot to foot in cheaper fuse. Usually while they build consumer cakes, there is a bit of factory error or flex in the amount of fuse used between shots. Other factors can affect the speed such as how and how long it was stored. Like Dave said the best way to plan out the timing is using pro line/articles pyrotechnics... I usually build boards of smaller cakes and overlap the fusing of each cake. Trying to avoid black sky and keep the audience oohing and ahhing. Used to try to have one start when one finished but it usually ended up either too fast or slow.