If you blast them on with an impact and consistently over torque the nut then maybe 6 months. If you take care of them, properly torque them, don't bang the wheels on the threads and start the nuts by hand then they last much longer.
I got 2 years out of the Vorshlag 75mm studs before replacing but won't do that again. I don't remember those being a total whore to get out.
I would immediately replace the studs on a corner if some nuts got loose on track. Especially the studs where the nut was still tight because they just took a beating.
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