I'm used to be sure you are supposed to get a lounge access if a connection DOM-INT or INT-DOM is less than 24 hours, not necessarily same day (in the calendar day meaning). I personally experienced that multiple times when flying with Air France, KLM, Aeroflot and Alitalia, even on separate tickets. A couple of examples:
1. A separate standalone ticket NCE-CDG with AF today and CDG-SVO with SU tomorrow, access at NCE with no issues.
2. Arriving with KLM AMS-SVO yesterday at 5 pm and leaving today with SU SVO-LED at 3.30 pm, access at SVO with no issue.

Is that the same with Delta? I mean it should be, but then again it's Delta. I checked the rules on lounge access and they mention same day connection between domestic and international flight is required to get access on domestic leg. Do they really mean same day or it's still 24 hours.

I would appreciate if someone can share experience. A couple itineraries I'm most concerned:
1. AF CDG-LAX arrival today at 2pm, then DL LAX-DEN departure tomorrow at 10am, separate tickets, access to SkyClub at LAX?
2. DL ticket: SAN-ATL-MEX, SAN-ATL overnight, ATL-MEX is on pretty short connection next morning. Technically those flights are not same day, even it's clear it's an international itinerary. Access at SAN?