I always click the link, wherever offered.

Last year my wife and I checked into 2 separately-booked rooms in a hotel (I'm a Diamond and my wife is a Gold); she had been offered an e-Standby upgrade and had clicked the link, my reservation did not offer me this option.

Result ? Her room was upgraded FOC, mine was not !

I thought it was a little strange, to be honest, and it was not very well explained by the hotel, but that's how it worked out.