I read for about half an hour a day, at least. But most of the time I read a lot more because I got addicted to it. On some sites they say it's best to read at least 1 hour a day, though.
I think reading 30+ minutes is a good time limit. Usually by the 30 minute mark, you’re fully engrossed in what you are reading, and after that it is much easier to maintain pace and read chapter after chapter.
So, reading is a must for your mental health. If you are really busy during the day, it will be great do read at least 15 minutes before going to bed. But if you have more time in the day you can read as much as you can, even three hours. You just need to find a great book and that's it . Have fun 🙂