Right. If it is a SHTF situation, it is useless unless it's affixed to the top of a fence or something. I can leap and clear a three spool wide, two spool high concertina barrier with gear and rifle at a full run. I'm sure possibly more if I'm desperate enough. That would be a lot of spools to secure a parimeter.It isn't much of a barrier.
Really only useful for turning a running man into a stationary target.
If you feel obliged to use it, it works best if allowed to become overgrown with vegetation