Certainly not harming a collectible gun so if it being pretty is important to you by all means. My personal opinion is refinishing is almost never worth while. If you have a finish work working gun and refinish it eventually it will accumulate wear again and you will be back at square one.
As most all of us know refinishing a collectible gun destroys the value.
On non collectible less expensive guns the money to me makes little sense:
$300 gun
$250 refinish
Value of gun after refinish pretty
Much still $300.
Some will talk about rust and such but even when I lived in a rather humid area never had problems with rust on my finish worn guns and I am not real fussy about keeping them oiled/ wiping down regularly or anything.
I guess if you live in the Deep South or other hot humid region and have a gun you carry frequently and found rust to be an issue, then perhaps it makes sense.
For a commonly available gun it might actually make more sense to just buy a new gun:
Current value of finish worn gun: $250
Cost to refinish:$200
Same gun brand new $500
For fifty bucks more sell old get new