I've learned in using scare tape for a lot of streamers that it very often cuts itself in flight. It's highly visible, but I've often seen two sections of it gradually drifting apart and have to guess by the decent rate which one has rocket parts attached to it.
I still recommend it, because it's extremely easy to spot when you launch a rocket down-sun, but I now consider each streamer I make with it to be a single use item.
Thanks for the 411. That seems to be a characteristic of Mylar (PET) with a cut edge. Any imperfections, nicks, and it tears easily.
Are you using the factory width or cutting the strip width yourself?
What type of scare tape are you using?
I was initially going to cut my own streamer from a Mylar space blanket, but it tears so easily I abandoned that for the raw material.
The "UGold" Scare Tape
I purchased has very smooth edges, likely cut with a hot knife. It's also thicker (0.001") than the Mylar (PET) blanket material (0.0007" ish).