This coming from a videographer, you "don't" have to blank a tape (to record just black on it)
It records a continuous time code onto the tape, which is important when you want to batch capture things onto your computer. If you don't blank them, what can happen is that the times you take the tape out of the camera/switch it on and off, ... the time code can be interupted. Result: if you want to capture the footage onto your computer into different parts (eg minute 1 to 5 and then minute 7 to 15, ...) it will "flip" on it.
Hope that makes sense to you