Overall, it's a risk assessment - how bad would it be if they got out?
In our case, their electric-fenced enclosure is within a stock-proof field which we own, so if they escape, they can't go far.
These are our first weaners, and I'll be honest, I was expecting them to wander at some point. However, much to our surprise, they have respected the tape no problem once trained to it, so it is possible.