Having just received a rebate in the form of a Visa giftcard, I was looking to spend it as soon as possible.
I like to get those things out of the way because it reduces the risk of forgetting or misplacing it and then missing out. One of the reasons companies like to issue gift cards is that many of them don't get used so it ends up being profitable and good for cash flow.
Xfinity accepts over payments at any time. Anytime I receive a rebate in the form of a visa / mastercard / etc card, I just log into my Xfinity account and a minute later, the card balance is zero.
I've even used Xfinity to meet time bound spending requirements for credit card bonuses.
In this case, I was even able to choose a virtual visa card, so didn't even have to wait for the physical card to arrive. All done within a few minutes of receiving the rebate approval email.