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I wouldn't worry about the 50 minutes - unless it is VERY important than you AND your luggage arrives in EWR the planned day.
No insurance necessary. SAS will deliver sooner or later, should it get stucked on the way. For a complete loss, SAS will cover as well, though there is a limit (which I don’t know). So if you have very valuable things checked in, it could be worth checking the limit.