I have been working on a project as a part of my studies(computer/data science). I tried to make the best classifier I can with what I learned, and recently I have tried to upgrade this classifier using new things I learned. I have tried using several ensemble methods such as bagging, pasting and voting, and the results I get are similar to using a single classifier or even a bit worse, but taking more time to run.
My question is, in which cases should you use ensemble learning, regarding to data size, data kind(text/images)?