It is definitely not 30 minutes long. That's her block, which will probably account for about 15-20 minutes of performance and then time for the switchover between acts.
What the setup like. If the setup is something like warp tour/CMA fest then this means she gets 30 mins. If it is something like CTI or RF, then this means she is getting 20 mins.
She'll do like 5 or 6 songs:
Make Me
DYWCO
New Song
Womanizer, WB or New Song
Slave
Toxic
If she rehashes Vegas I will riot. Also, I'd much rather her doing idk BOMT/OIDIA than Womanizer or Slave but I feel like it's more likely she'll do either one of those.