Absolutely right. And the thing is, the more you test things, the more comfortable you become with the concept of testing by actually downing stuff. You need to be cautious not to get complacent, of course, and start carelessly skipping steps of the run-book, but you feel a whole lot less trepidatious doing your fifth or sixth monthly test than you did doing the first :-)
One does have to be careful, though, that if you implement a manual trigger the behaviour must be *exactly* identical to what would happen with a real outage. As a former global network manager I've seen link failover tested by administratively downing the router port, when actually killing the physical connection caused different behaviour.