Do all mods need to have a new save to update or just ones with scripts?

[BlackArk]

Well mistakenly posted something to the wrong place, had two tabs opened but I decided to just edit it.
 

I was thinking of updating some pretty big mods and was wondering if I need to start a new game again.

[有限な]

To be 100% safe, I would start a new game. 

[TnTTnT]

Mostly adding new mod into game doesn't need to start a new game.  However, to be save keep the save before install new mod for backup purpose.

 

Upgrade version of existing mod is another story, my practice is start a new game to test working combination first and then use main save (do clean save first if possible).  Save file cleaner also a life saver if anything goes wrong.