Being a very avid gym goer/weight lifter myself I am a person who considers the gym to be my home away from home. having said this I know your next question is going to be "Do you take any day off from the gym and are rest days needed in order recover efficient?".
Well to answer that question first let me explain my routine in the gym. I am currently on a four day on one day of split in which i train my upper body for three days making sure to group muscle together in each workout by targeting and working agonist and antagonist muscle groups together in each session. On the four day of this style of programming i work my legs alone as they are the largest muscle group on the body and need the most attention.
I find this to be the most effective form of programming for my current stage of development as I benefit from three days of very intense, vigorous military like upper body style workouts and then allowing my upper body to cool down, rest and repair itself on the forth day while putting my legs through a long and extremely intensive assault course consisting of heavy lifting and lots of compound movements and drills. I then rest the entire body for two days and repeating the exact drill the following week.
Now having giving you a little insight in how i train in the gym i can now go on to answering you the question "Are rest days needed?).
Well the answer to that question is yes but it depends on your current level of conditioning. For example a noobie lifter in the gym that has never lifted weights in his life would require a rest at the very beginning of his/her fitness journey, whereas a moderate well conditioned individual who has been training for a while might not need a days of baring in mind that he/she is training to maintain their current level of fitness and conditioning and not training to compete in a physical or competitive sport or weight lifting tournament.