Does anyone have a backup plan?

Not selling tickets mods, just looking for advice from anyone who’s bought 3rd party and if they have a backup plan. I got a stub hub ticket for DC and was wondering what my backup plan should be if I were to get denied at the gate and stub hub says they can’t get me a ticket and gives me a refund. What should the backup plan be to try to get in? Check box office and if not then should I be refreshing Ticketmaster or seatgeek outside ? Or?