Every once in a while I come across an Incursion as I roam through lowec. I don’t think I have ever seen one being run. Usually they are bad news because they suppress bounties and increase the damage taken at sites.
However, one very nice thing about Incursions is that they occur way outside the solar system – sometimes 25AU or more outside the solar system. As such they are VERY handy for making deep safe spots where you cannot be seen on d-scan from any celestial object. I rarely needed deep safes before, but with the addition of mobile depots, I am starting to use them again. You can bookmark 2 incursions and set up a safe spot between them. Your mobile depot can still be seen by combat probes if they are set at a large enough distance, but most people will not think to do this. Out of sight (of d-scan) = out of mind.