I agree with checking the tension of the spokes. You don't want them banjo-string tight. You do want them tight. The object of the game is that the wheel is suspended in tension. The greatest load is taken by the spokes on the top of the wheel in it's rotation. With the tension balanced (at rest) between all the spokes the wheel is kept "round". As you put more and more miles on the bike the spoke tension can settle and change causing the wheel to go out of round (usually not too bad). The object of the game is to keep up with it.
And that reminds me - I need to do the same on my touring bike. The wheels aren't "bad" by my book, but I can see a bit of wobble so they are due for a truing.
I wouldn't consider a broken spoke a catastrophe or a ride-killer. If I broke one (never have yet) I'd tape the pieces to the next spoke and keep on keepin' on.
If spokes were popping left and right then there would be something very wrong with the wheel - most likely too much tension. That or a defect in the spokes.
If spokes are spaced out far enough around the wheel I wouldn't even consider 2-3 spokes ride-killers. If they are all in the same quadrant or so then it might be a bigger issue.
Of course, it is best practice to replace spokes - but my point is it isn't a road-side repair, nor should it be considered a ride-killing mechanical. Bandaid it with some tape to secure and move along. If you're on tour - maybe that could be an evening project. Or if you are a day out from a better place to do the work than in camp - carry on for a day and get there.
Once a spoke is replaced - what should you do? Make sure the tension is set properly in the spokes and keep on keepin' on.
Good luck!