RCI Terms and Conditions are available through a link at the bottom of the RCI site once you're signed in. For points, the terms for cancellations are in clause 14, which starts on page 11. They include the following:
14.A.i.a. If a Member makes a Confirmed Exchange three (3) or more days prior to the check in date and the Reservation is cancelled before the end of the next Business Day following the date on which the Confirmed Exchange was made, the Member will receive a full refund of the Transaction fee paid for the cancelled Confirmed Exchange.
14.A.i.c. If a Member makes a Confirmed Exchange two (2) or less days prior to the check in date, the Member shall not be entitled to any refund of the Transaction fee paid for the cancelled Confirmed Exchange regardless of when the cancellation occurs.
14.A.ii.a. If a Member confirms a Confirmed Exchange fifteen (15) or more days prior to the check in date and the Confirmed Exchange is cancelled before the end of the next Business Day following the date on which the Confirmed Exchange was made, 100% of the RCI Points used to make the Reservation will be refunded to the Member’s RCI Points account.
14.A.ii.b. If a Member confirms a Confirmed Exchange fourteen (14) days or less prior to the check in date and the Confirmed Exchange is cancelled before the end of the next Business Day following the date on which the Confirmed Exchange was made, and the Member has not purchased Points Protection, 25% of the RCI Points used to make the Reservation will be refunded to the Member’s RCI Points account.
They define a business day on page 1 as: The regular business hours of operation for RCI’s Carmel, Indiana Call Center. On the contact us page, they give the business hours as Monday-Friday 8am-8pm(Local time), Saturday 8am-5pm (local time), closed on Sunday; holiday hours vary.
For weeks the terms for cancellations are in clause 18, which starts on page 13. They include:
18.A.i. If a Member makes a Confirmed Exchange three (3) or more days prior to the start date and the Confirmed Exchange is cancelled before the end of the next Business Day, the Member will receive a full refund of the Exchange Fee paid and the full Deposit Trading Power used to make such Confirmed Exchange
18.A.iii. If a Member makes a Confirmed Exchange two (2) or less days prior to the start date and the Confirmed Exchange is cancelled the Member shall not be entitled to any refund of the Exchange Fee paid regardless of when the cancellation occurs. The Deposit Trading Power, or a portion thereof, used to make the Confirmed Exchange shall be redeposited into the Member's RCI account. The amount of Deposit Trading Power redeposited into the Member’s RCI account shall be recalculated in accordance with the Trading Power Adjustment Schedule found on RCI.com unless the Member has purchased Trading Power Protection in accordance with Par. 14.
Bottom line would be that it's not really 24 hours, but instead until the end of the next business day as long as it's not an exchange within two days for the transaction fee (or fourteen days for the points). If you're talking about either weeks or points and you made the confirmation yesterday (Sunday, 12/24) or today (Christmas Monday), while they're closed, you should have until Tuesday, 12/26 at 8 pm local time in Carmel Indiana to cancel without losing points, trading power, or the transaction fee. The rest of the terms and conditions in those paragraphs tell you how much of the points or trading power you'd get back if it goes beyond the end of the next business day.