Amphenol typically lists 100 mating cycles for D-Sub contacts with gold flash plating, which is considered less than 10u" of gold.
As an example, see manufacturer response below regarding the mating cycle for Amphenol L717DB25P:
“Since the contact area plating is gold flash, we understand L717DB25P can support 100 mating cycles.”
Below is also a snippet from the datasheet:
*This may vary contact to contact, the datasheet will have to be reviewed on each specific product.
CONN D-SUB PLUG 25POS SLDR CUP