That is exactly the point... the girl is not going to want to sleep with him simply because he showed her a good time. She either wants to sleep with him or she doesn't.
Assuming that the girl has some interest and the guy knows what he is doing, MOST (95%) girls will sleep with him within the first 3-4 hrs, religious, shy, whatever - that is all irrelevant.
No girl who is hooked on some guy is going to care whether he picked-up the tab or not. We aren't talking about "just sex", we are talking about getting girls addicted to us, preferrably for the purpose of some genuine relationship.