I've had one of my diamond cut brescia's refurb 3 times now, admittedly the 3rd time was a push but the wheel company are very good. I think it depends how much they skim off each time.
Hopefully the refurb company used are professional / reputable and wouldn’t consider attempting a third full refurb of a diamond cut alloy if the outcome would be a potentially unsafe wheel. Normally, diamond cut alloys can only be refurbished a maximum of twice; two refurbs and usually a wheel will be at the limit in terms of how much metal can safely be skimmed off the face before the structural integrity of the wheel might be compromised.