You up your chance of sex if you pay for shit. Throughout history women essentially sell their bodies to men. The only men they fuck because they want to fuck is Chad. Having sex with any other guy is basically through a form of beta-bux.
I used to think I'd always make the girl pay for herself, but now I think you have a higher chance of fucking her if you just pay for stuff. Just don't get carried away, because women will gladly take all your money and give you nothing in return.
This girl I orbited for a few months told me she used to go on dates with guys for free food, and occasionally would fuck them just because she felt like she had to. But if you haven't fucked her by date #3, refuse to pay for anything else, because she's almost guaranteed just taking your money.
I think more important than buying her shit is just showing that you have wealth. Women are attracted to guys with money, albeit not necessarily sexually. But yeah... most girls have fucked Chad many times without going on dates. She only makes normal guys pay for it.