I quite like the idea of iCloud Photo Library - keep the full res pic in the cloud and the smaller res pics on the phone. Makes perfect sense.
Yes I'm fine with that approach.
Under Windows it's quite different: photos are stored in Onedrive AND on the phone, so if I delete a photo on the phone, it is still present on Onedrive and I have to delete it also there. A waste of time.
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I just have OneDrive upload any new photos and videos from my iPhone. That way it doesn't matter if you delete them from your phone as they are all still there and accessible from multiple devices.
Yes, so if you need to delete one you have to do that twice.... what a brilliant solution