None of these "experts" even understood your question.
"How does the IRS define a gambling session for sports gambling?"
The netting of gains and losses greatly differs depending on how a gambling session is defined.
There is nothing the tax code on the matter. It refers to "transactions" to imply you do have the ability to use some sort of grouping. I think a 24-hour period is the most likely answer from the IRS. Defining a session by sporting event or sports season might be a possibility. I do not think you can use a full year on a sports betting site to define your session. Otherwise, the whole concept of the tax code for a casual bettor would match the general netting allowed for a professional gambler and thus not make sense.
I think you may have to keep separate 24 hour results for the different gambling sites as well.
