If you're replacing the nut because its sub par then probably there's a lot of stuff on the guitar thats sub par. By the time you replace all that sup par crap you could've just bought a better guitar.
If I'm playing the guitar and enjoying it then nothing wrong with keeping it the way it is. I've never owned a guitar where I thought changing the nut is going to give me a much better guitar.
Well I had one where replacing the nut made a difference.
I've only ever replaced one--it was cheap plastic.
I did replace other stuff as well--including the pickups--but for what I paid I now have a guitar I play, instead of letting it sit in its case.
And for what I paid for all of it I could have bought a new guitar--but a cheap one that I probably would have replaced stuff on any way to make it as good as what I have now.
And I don't care about resale (I would probably get more money out of it if I put the old pickups back in & sold it that way & sold the new ones separately.-but I know I'll never get the money back)--but the point was to have a guitar I would use.
And that worked.