These slot players in the cited example had a "constructive receipt" and yet were able to net their slot play on MULTIPLE machines & MULTIPLE transactions to reduce their tax burden.

The better view is that a casual gambler, such as
the taxpayer who plays the slot machines, recognizes a
wagering gain or loss at the time she redeems her
tokens. We think that the fluctuating wins and losses
left in play are not accessions to wealth until the
taxpayer redeems her tokens and can definitively
calculate the amount above or below basis (the wager)
realized. See Commissioner v. Glenshaw Glass Co., 348
U.S. 426 (1955). For example, a casual gambler who
enters a casino with $100 and redeems his or her tokens
for $300 after playing the slot machines has a wagering
gain of $200 ($300-$100). This is true even though the
taxpayer may have had $1,000 in winning spins and $700
in losing spins during the course of play. Likewise, a
casual gambler who enters a casino with $100 and loses
the entire amount after playing the slot machines has a
wagering loss of $100, even though the casual gambler
may have had winning spins of $1,000 and losing spins
of $1,100 during the course of play. [Fn. ref.
omitted.]