This app has been out for a while and it is SUPER handy.
It’s called “Ballroom Competition Trainer”.
We use it all the time and once you get the hang of setting it up, it has been immensely helpful for practicing rounds. It’s handy to have some playlists ready for easy linking (although you can make rounds linked to specific songs). I have playlists for each dance that are already at competition speed so every time we run rounds, it will pull random songs from the playlists.
It has templates set up for both international and american styles, although you could program it to any type of session you want (say you want to do Samba 10 x in a row…. although i’m not sure why you would LOL!).
One of my favourite features is that you can enable “randomizing” for the lengths where you chose (for example) “Dance for 1:30 – plus or minus 10 seconds”. Same for the rest periods.
It’s a great app, and will save you from having to run back and forth and play DJ while trying to get in a competition simulation!