[ There's a reason that years and years ago when she was young and had to teach herself shields she just used the generic image of a house, the one the book suggested. There's also a reason she doesn't recommend it. Her shields don't actually resemble that house anymore so much as they look like a prison, less like rooms than cells locked down. ]

It's a balance. You don't want something sensitive enough that it would compromise you if people got through it, because these aren't a fix-all. Emma? Anyone on her level can rip through shields like this as soon as they put some real effort into it. These are for blocking low-level telepathy types.