Cites:

http://www.gambling-law-us.com/Artic...bling-session/

U.S. taxpayers, with the exception of some professional gamblers, are not allowed to ‘net’ their wins and losses (that is, combine them and report only the total), but must add up their total wins from each gambling session and report the total as income (part of ‘Other Income,’ line 21 of Form 1040.) Losses in any year may be claimed, but only up to the amount of winnings reported that year, and then only if the taxpayer elects to itemize deductions rather than taking the standard deduction.
And here's an article quoting from a tax decision regarding session parameters:

https://taxattorneyoc.com/blog/2019/...ur-tax-return/