I have a 6-hour layover at Newark airport on an international flight to Scotland. I'm concerned that my luggage may not make my connecting flight with such a long layover. Should I check bags to Newark then claim and recheck or just hope they arrive at final destination with me?
The problem is never a too long connection. I've had significantly longer connections without any fault. Short ones, under 30 mins or so, though have had less luck but it has been very good lately. They will even label your bag with a Hot Connection sticker to tell people that it needs to move fast.
It is best to check your bag through which is usually done by default nowadays, unless your itinerary prevents it which they would tell you at check-in or baggage-drop, if you did your check-in online.
Claiming and rechecking first would require the airline to accept to short-check you bag. They can do that but they can also refuse. Then it forces you to exit the secure area and pass security again later, so lots of time wasted. If you have such a long connection, I would imagine you might prefer to rest and not go through unnecessary procedures.
Long layovers are actually the safest way to get your luggage transferred... I don't see the rationale behind "long layover = missed bagage connection"...
In Europe and Asia, if you transfer between two airlines that are not in the same alliance, they often require 4 hours between flights -- whereas one hour is considered safe for flights between the same airline and/or alliance. So longer layovers do work for you.