The cuts in the nut really serve two purposes:
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Supposing there's no 0-fret, they let you set the action height at the headstock end of the fretboard.
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Set string spacing at the headstock side.
So, in my opinion, try to keep the tolerances close but with a bit of room for movement. You want to be sure that the strings can slide when tuning and fretting notes without getting caught, which can mess with tuning. Especially with a floating bridge.