Couple things I don't agree with.
If you don't change the filter you don't remove all (or at least as much as you can) of the dirty oil. It's not that expensive - change it every time!
No need to change the oil again in spring if you have used synthetic oil and not run it during storage.
The biggest issue caused by running for short periods is the production of moisture, but not in the exhaust, in the oil. Each start-up adds moisture, acids, and unburned fuel to the oil.
Running at operating temp for an extended period of time, and limiting the time it takes to warm-up (riding gently to warm-up, not idling), will help limit and reduce most of those contaminants.