This is definitely a commitment not to take lightly, and having just sat L3 for the first (and hopefully only) time this exam does become all consuming so some spillover into social life and family is almost inevitable. A lesson I learnt when I resat L2 and carried over to L3 was that you can never start too early, so I began reading the material in September 2018, aiming to finish by Christmas giving me c. 5 months of question and mock exam practice. A couple of months out I decided to set aside one day a week when I did no study (normally a Sunday) as I noticed my performance in questions was sub-par and felt I needed a full day away from the material to reset.
Is it possible to have “balance”? Probably not, but if you plan your time well there is no reason you cant have a night off a week to do something else. Also helps to know that studying won’t be forever…