It depends on the person and the specifics of the diet. A good multi is meant to fill in the gaps from your nutrition. That being said, I recommend taking one. Check out 3DMulti from n2bm.
If you get older, say 50+ is it really necessary to run a multi vitamin or will you be fine if you just eat a lot of nutritious foods? I was talking to a friend and he is in his 60’s and says he has been taking them daily for 20 years and he says it makes a huge difference in his health