I would not push the button in the first 24 hours of illness. If after that I was getting significantly worse, then yes.

I schedule at least one contingency day in every trip, two for longer trips. This avoids having others panic if I am a little late. Yes, it adds some danger, but I have the supplies for those two extra days so I really am not in a lot of trouble.

I think PLBs really are quite useless if you have only one option - push button or not. I would not even get one if it did not have at least two functions - button for "rescue me" and another for "warning -having trouble but do not resuce me".

There are also other options than full-on call the SAR. Maybe the first step is for a group of friends to look for you. Not call in the SAR right away.

Perhaps you need to devise a plan or action for several scenarios. Write this down so your wife has a set of instructions to follow. Sort of like a decision tree. For example, 1 day late; weather good = wait 24 hours, weather poor = start step 1 of rescue (maybe step 1 is notify a group of friends and be ready to go out and look in 4 hours).

Just some thoughts.