You definitely learn a lot in years of running. How to deal with and prevent a range of typical running injuries, and what can and can't be run through.
It sounds obvious, but anything that changes the way you walk, or gives pain to walk, is ridiculous to run through.
However, just tightness, can usually be run off pretty easily.
I've also found some injuries actually need "active rehab" rather than rest, such as groin strains, toe problems, and ankle problems...
it just takes time to find out what to do in each situation, and appreciate how the different parts of your body come together.
For instance, my hamstring has been a bit achy for a while, so I stretch it loads. The 2 day ankle lay off then came along... It's pretty likely it was a weak calf muscle causing both of these effects, even though there was little pain in the calf!