Some ARF's just come with better quality hardware then others. I just go through the kit and see what looks usable and what needs to be replaced. Normally always like to replace the fuel tank even though the supplied one might work. I guess it's more a habit. I like to use carbon fiber as pushrods on my planes. Hinges are tossed out also most of the times. Of course you must look for weak spots and then fix or re-glue. I also replace the engine mounts on some of them. If the wheels are to heavy they are exchanged too.
That's about it.