I expect they can, considering we're currently dependent on our phones to evoke them. That would be why it isn't practical, a defence you can't use against the true enemy is barely one at all.

The Life Coach said we may be able to learn to use them independently, however. Should I achieve that, well, then I'll change my opinion. [Said with a sunny smile and maybe a bit of a wink. He may or may not be actually trying to fluster Akechi.]