I am in the same boat as you, 2 children at home (3 and 2 years old). Just took GMAT last week and scored 550 after months of hard work. I am a non-native (French Canadian) and never had math courses.
I need 680+ for a good PhD. Usually, I read verbal books during the day and practice during the evening-night. Put around 5 hours a day.. Lost 10 pounds in couple weeks, it's very hard.. Plan to retake the exam on December 13th. Hopefully will be done soon..
To anwer your question, me I did that (just practice questions) but in my opinion, read books is important to get knowledge of the fundamentals. Books give a lot of good strategies.
MGMAT are amazing, especially Number Properties, SC and RC. Just finished Powerscore CR, which is VERY good.
GMAT Club test too. Highly recommended.
Good luck for you! We will kill the beast