For NR wire: I leave them around 40mm (positive) and 30mm (negative) in length.
But there is no rule, it depends on each one, after some setups you will know what is the appropriate length to work comfortably.
Sometimes I tend to use less wire (to save some), but it can complicate a little the setup.
For R wire (Kanthal A1, 32 AWG): I think that around 25 mm or 26 mm will give you 1.5 ohms (taking in cosideration that the NR adds a little resistance), for a single 1.5 ohms coil.
For a quad coil configuration with a total resistance of 1.5 ohms, each coil must be of 6 ohms (around 13 cm of Kanthal A1, 32 AWG for each coil).
The lengths of resistive wire (Kanthal A1, 32 AWG) I'm providing were taken by me, but this calculator will help you a lot:
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