There is a "30 minute warrior training limit 440%" item which works wonders. However I think you can only obtain it from one of the checkpoints in an event - can't recall which one, (not troop training).
Building more barracks is good but the trade off is waiting much longer for troops. I just had one barracks and set a reminder on my phone for when the training finished so could log in and train more.
I guess the only real advantage of being able to train a lot of troops at once is you could set up a lot of high level troops to finish in time for clan battle, if you have enough resources to train that many troops.
This has just been posted by Alice(admin).
https://plarium.com/forum/en/vikings-war-of-clans/666_game-database/132143_table-of-main-bonuses/
A very useful table, which might answer your specific question, and many others as well.