Wearing Tefillin during Mincha and Study Time
Question
In these days (on the eve of the Day of Judgement) when we are doing a lot to add merits, I thought maybe it would be worthwhile to put on tefillin during Mincha and study time. I wanted to know if there is any problem with this.
Answer
Dear …!
Already in ancient times, it was established not to wear tefillin all day, even though this is the basic commandment, since it is difficult to be careful about sleeping with them, being distracted, and being lightheaded. They said that one should wear them only during the time of Shema and prayer, as for a short time one is able to be careful.
And it is clear that it is better to refrain due to doubt, and not to add.
Therefore, for anyone who is not confident that he can be careful about this, it is better not to add time of wearing them, so as not to commit a prohibited act while wearing them.
However, during Mincha prayer, it is easier to be careful about this. And it seems from the words of the Biur Halacha that it is permissible to put them on.
Source
Shulchan Aruch Orach Chaim 37:2, and see Biur Halacha there