I'm presuming these ideas are for legitimate purposes, mainly working overseas in areas where kidnap is a threat, or where your work makes it one. Obviously any authority worth their salt will find these basic preparations, and then you'd be in more trouble than when you started.
In which case, they'll probably be utilised daily and therefore should be unobtrusive as possible. If you're certain enough that you'll be kidnapped that you're willing to shove a flint up your nose, maybe you should reconsider your plans.
Handily, most criminals don't think too hard, and would be unlikely to imagine you're prepared.
Absolutelly for legitimate use.
As for rethinking a trip if concerned of being kidnapped or whatever, while I see where you're coming from and would normally agree, we cant' always pick and choose were we go and when, at least for some. Even then if that was the case, bad things happen to good people in good places ALL the time. I've been all over Central America and most of the Middle East and I can tell you from experience sometimes it's not as simple as just choosing not to go. It's about risk management and setting things up as much as possible in your favor should Murphy show his face. One thing I've learned over the years of being in those enviroments is never say or think that something wont happen, because when you do that's the day it will bite you in the ass in a manner that if your lucky you'll get to go home and see you family again.
I'm just thinking out of the box here.