Do not worry about how long it takes to read one of the Hours of the Passion. Many of the Hours can take only from 5 to 10 minutes to read carefully and meditatively.
In the beginning you may find it difficult to meditate for a complete hour due to lack of time, especially when it comes to one of the longest hours such as the Hour from 11 A.M. to 12 Noon (The Crucifixion of Jesus). In this case, you could split the meditation into two or three moments at your convenience.
If you cannot fully complete the hour due to lack of time or unforeseeable circumstances, you can substitute your commitment with the righteous intention to read the hour and to be with Jesus in His Passion.
In fact, in the Prayer of Preparation before each Hour, we say:
"...And for those hours which I cannot meditate, I offer You the will I have to meditate them; and I propose to meditate them with my intention during all the hours I must dedicate myself to my duties, or sleep.” (The Hours of the Passion, Prayer of Preparation before each Hour).