I typically attempt to not cut the membrane. However, this is not always an easy task. I would say that 95% of the time I cut it, because I can't avoid it. The primary concern here is to cut as few veins as possible.
Couldn't have said it better!
0.1 Vanilla Ghost
1.0 Vanilla 100% Het Ghost
0.1 VPI Ghost
1.1 YB's
1.0 Spider
0.1 Het Albino
0.4 Normal's