Heya! It is perfectly fine to revise one subject per day. In fact, it is often recommended to focus on one subject at a time so that you can give it your full attention. This will help you to retain the information better and to understand it more deeply.
However, if you find that you are getting bored or restless, you can always switch to another subject for a while. Just be sure to come back to the first subject later so that you don't forget anything.
Ultimately, the best way to revise is to find a method that works for you and that you can stick to. If you find that you are able to focus better when you revise multiple subjects per day, then go for it! There is no right or wrong answer.